Because none of us is required to wear shirts or shoes to go in a store. Nothing like that already exists. I don't even have to wear a top to the beach any more!
(The Supreme Court recently ruled that I must wear a top to the beach - even though I woke up in a free country too and that sounds suspiciously like sex discrimination - go figure).
Oh, and shirts and shoes required for established is a very old rule. I can't even imagine what public health would be like if everyone was allowed to wear whatever into any store or restaurant.
Also, remember "We have the right to refuse service to anyone!" (And that's still true as long as it's not systematic discrimination against a protected group).
Homeowners' Associations can still ban people under a certain age if they are a private holding.
In some states, you can't be visible in your underwear (or cuss) even inside your own home if others can see or hear you.
It's interesting to me that so many apparently think "freedom" means "I can do anything I want." They had to close a big section of highway near a popular hiking trail (and close the trail) because people were parking illegally with part of their cars in the highway, on a bridge, in places with no shoulder, etc. So they towed 'em. And this morning, it's all coned off - but some people STILL parked illegally, trail is closed to everyone indefinitely, and yep, they'll be towed again.
Because we do not have the freedom to break laws or disobey store policies.