We also had homeless people use restrooms to bathe, and drug addicts use the bathroom as a place to quickly take a hit. Also had people defecate on the floor, write messages on the wall with feces, etc. Because of this, multiple places I worked didn't provide restroom access to the public. It sucks for people who simply and respectfully use the restroom. But at the same time (in one specific location at least), it was a matter of having to clean up fecal matter or drug paraphernalia or not letting the public use the restroom. My sub-living-wage job simply didn't pay me enough to put up with that crap.
That being said, if you let 'customers' use your restroom, you should let gig workers do the same. They aren't your direct customer, but show them a modicum of respect and dignity.