Also, to point out, you asked "You're telling me the ADA requires an audio device to be given to people who can't hear."

That may sound silly, but one of the more common devices used to assist the hearing impaired is a radio that interacts with hearing aids and cochlear implanted devices. So, in a manner of speaking, they are using audio devices to help people who can't hear (that are not completely deaf at least... otherwise hearing aids would not be a thing).

The reason I brought up blind people was because you said that the ADA applies to every business that serves the public, and asked why movie theaters were be exempt. I attempted to make the point that movie theaters are not exempt, but that the ADA does not cover all disabilities at all times. There are ADA requirements for movie theaters to accommodate those that need hearing assistance (whether they be blind or hard of hearing). So the ADA does apply to movie theaters. It's just that, like all other applications of the ADA, there are exceptions and there are areas of disability that are not covered for various reasons.