i've been accosted and kicked out of places so many times for being barefoot: grocery stores, restaurants, a bar, book shops, even a shoe store. i've basically been bullied by society at this point into wearing shoes whenever i go out, despite my own preferences. it's not illegal, basically anywhere, but you've been quite lucky to not have gotten any shit anyways.
Those places don't want to take liability for you potentially getting injured. Even if you would never sue a place for that, they have no guarantee of that, and US liability laws are absolutely ridiculous. I hope the US fixes the liability/lawsuit culture. So many things get killed by it
(For the record, I'm not one of the barefoot people. I find it weird, but to each their own)
yeah, that was my issue at the time, my shoes had finally completely fallen apart on me and i needed a new pair for something. they fortunately let me finish my task when i explained my predicament.
If you're anywhere near a beach, I wouldn't be surprised.
Go a few hundred miles inland and to conservative land, and you might hit some resistance. Even if it's not from the employee who's not getting paid enough to give a fuck, it'll be some old crotchety lady that needs you to know your bare feet are ruining her life.