Those “No Shirt, No Shoes, No Service” signs really seem to be a recent phenomenon. As Professor Terry Anderson noted in his book, The Movement and the Sixties:
Citizens reacted to the hippie threat in many ways. Country-western singer Merle Haggard condemned the counterculture in his hit tune, “Okie from Muskogee,” and singer Anita Bryant held “rallies for decency.” Southern Methodist University officials attempted to stop mail posted to the campus address of “Notes from the Underground,” while a group of alumni and students threatened violence if the “filthy sheet causing embarrassment” did not stop publication. Businessmen across the country put up door signs, “No Shirt, No Shoes, No Service,” while Marc’s Big Boy in Milwaukee hired a cop to make sure that no one with beads, beards, flowers, sandals, long hair, or funny glasses was allowed inside to buy a double hamburger.
Those signs were nothing more than the reaction of stores to hippies. Labeling them as “no shirt, no shoes” was simply the easiest way to keep them out.
Furthermore, this conclusion is reinforced by researching other sources. If one looks at many on-line newspaper and magazine resources, the earliest one can find a reference to such a sign is the early 1970s. The sign just didn’t exist much before then.
Of course, the signs spread like wild-fire, and before too long people became convinced that the signs were required by Health Codes (they’re not). These days, most stores do not have such signs, but the myth of the Health Code lives on. Also, folks have become conditioned to think that such signs are on the doors of every establishment, and I am regularly asked about such signs. But if you take the time to look, there are only just a very few stores (CVS comes to mind) that have those or similar signs.
Regarding Health Codes, the Society for Barefoot Living regularly writes to the Departments of Health for all the states to confirm that there are no such Health Department requirements. You can see the resulting reply letters here.