Poorly designed websites can create unnecessary barriers for people with disabilities, just as poorly designed buildings prevent some people with disabilities from entering. Access problems often occur because website designers mistakenly assume that everyone sees and accesses a webpage in the same way. This mistaken assumption can frustrate assistive technologies and their users. Accessible website design recognizes these differences and does not require people to see, hear, or use a standard mouse in order to access the information and services provided.
Being one-third of the way into 2019, we opted to follow up on the 2018 discussion we had regarding ADA Website Compliance. Per last year, making sure your website is ADA compliant is significant in offering an equal opportunity for everyone to experience the products and/or services your business offers. An ADA compliant website also help prevent lawsuits and potential government action.
Title II of the ADA prohibits discrimination against qualified individuals with disabilities in all programs, activities, and services of public entities. It applies to all state and local governments, their departments and agencies, and any other instrumentalities or special purpose districts of state or local governments. It clarifies the requirements of section 504 of the Rehabilitation Act of 1973, as amended, for public transportation systems that receive federal financial assistance, and extends coverage to all public entities that provide public transportation, whether or not they receive federal financial assistance. It establishes detailed standards for the operation of public transit systems, including commuter and intercity rail (e.g., AMTRAK).
If posted on an accessible website, tax forms need to be available to people with disabilities in an accessible format on the same terms that they are available to other members of the public – 24 hours a day, seven days a week, without cost, inconvenience, or delay. A staffed telephone line that sent copies of tax forms to callers through the mail would not provide equal access to people with disabilities because of the delay involved in mailing the forms.
“The idea of equal access, equal opportunity has sort of evolved in its application from brick and mortar to eCommerce. At first, many companies were worried about the desktop experience. Now, the concern extends to both smart phones and devices.  Wherever a consumer accesses your content – whether it be directly through the web or an app – you need to be concerned about accessibility.”
There have been some notable cases regarding the ADA. For example, two major hotel room marketers (Expedia.com and Hotels.com) with their business presence on the Internet were sued because its customers with disabilities could not reserve hotel rooms, through their websites without substantial extra efforts that persons without disabilities were not required to perform.[58] These represent a major potential expansion of the ADA in that this, and other similar suits (known as "bricks vs. clicks"), seeks to expand the ADA's authority to cyberspace, where entities may not have actual physical facilities that are required to comply.
I own a medical practice in California with 5 employees. Since I have under 15 employees am I exempt from needing to have my website comply with the ADA? I know that my physical practice is exempt from ADA policies regarding employment (under 15) but I don’t know if that extends to websites. My website is not an important part of my practice and I don’t really want to sink any funds into it if I don’t need to.
Until the ADA is updated to address the special case of website accessibility, or the Department of Justice releases its website accessibility regulations, complying with WCAG 2.0 Level AA is the best way to ensure that people with disabilities have equal access to your website. The overview below is a great starting point about meeting the WCAG 2.0 Level AA recommendations.

Prohibited discrimination may include, among other things, firing or refusing to hire someone based on a real or perceived disability, segregation, and harassment based on a disability. Covered entities are also required to provide reasonable accommodations to job applicants and employees with disabilities.[16] A reasonable accommodation is a change in the way things are typically done that the person needs because of a disability, and can include, among other things, special equipment that allows the person to perform the job, scheduling changes, and changes to the way work assignments are chosen or communicated.[17] An employer is not required to provide an accommodation that would involve undue hardship (significant difficulty or expense), and the individual who receives the accommodation must still perform the essential functions of the job and meet the normal performance requirements. An employee or applicant who currently engages in the illegal use of drugs is not considered qualified when a covered entity takes adverse action based on such use.[18]

Input Assistance: When users are entering input into the website, any input errors are automatically detected and written out, providing, for instance, text descriptions that identify fields that were not filled out or data that was in the wrong format. The website also provides suggestions to fix the errors. Input fields and buttons are labeled to provide their functions and instructions. If the user’s input is being used for legal purposes or financial transactions, then the user must be able to reverse submissions or correct errors.

The Supreme Court decided under Title II of the ADA that mental illness is a form of disability and therefore covered under the ADA, and that unjustified institutional isolation of a person with a disability is a form of discrimination because it "...perpetuates unwarranted assumptions that persons so isolated are incapable or unworthy of participating in community life." The court added, "Confinement in an institution severely diminishes the everyday life activities of individuals, including family relations, social contacts, work options, economic independence, educational advancement, and cultural enrichment."

UPDATE: Since writing this post in August 2017, several important changes have taken place in the laws regarding ADA compliance for websites. On December 26, 2017, the Department of Justice announced that they have withdrawn the Obama-era Advance Notice of Proposed Rulemaking mentioned in this article which intended to require ADA website compliance. The DOJ’s withdrawal announcement stated, “The Department will continue to assess whether specific technical standards are necessary and appropriate to assist covered entities with complying with the ADA.”
So, what do I mean by that? That sounds weird. So, when I say designer, I mean someone who's strictly an artist, and there's a lot of those out there. A lot of 'designers' are only concerned about the aesthetics of the site. What it looks like, or if its unique, or if it follows the latest website design trends. But at the end of the day they don't really 'get it' when it comes to what the primary purpose of a website is.