Unfortunately people take the piss (literally) and can be pretty vile in toilets, leaving a trail of destruction behind.
It's why councils refuse to keep spending endless amounts of money repairing them before they're destroyed again.
Why should businesses make their toilets open for all and sundry, exposing them to an even greater risk of them being trashed, the need to maintain them and, as a result, actual paying customers potentially being put off from using the establishment cos the public can't be trusted.
Of course paying customers might be as bad as the main wandering in off the street, and tbh I'd be in support of it being allowed if government or local authorities gave incentives to companies that keep them open, so the increased maintenance costs are absorbed.
Until then let private businesses operate as they wish.