Wednesday, May 20, 1998: No shoes, no shirt...

[Burning Sheep Productions]

This strip is the only place I've ever seen such a sign.

[Muninn]

They very quickly seemed to go out of fashion a decade or so ago

It's because comic strips and stand up comedians started making this joke.

[Cactus Jack]

I'm sure places of business bought signs people rarely pay attention to because of comedians. Thats how businesses work, they often enforce their rules only if comedians acknowledge them first.