The US courts are currently split on this. The 9th and 11th circuits hold that a business website must correspond to a physical business to enforce the ADA on them. The 1st Circuit has required fully online businesses to also have ADA accessible websites. There are exponentially more lawsuits on thus issue each year so expect the Supreme Court to address it in the next couple of seasons.
Is this legal in the US?
The US courts are currently split on this. The 9th and 11th circuits hold that a business website must correspond to a physical business to enforce the ADA on them. The 1st Circuit has required fully online businesses to also have ADA accessible websites. There are exponentially more lawsuits on thus issue each year so expect the Supreme Court to address it in the next couple of seasons.