"Bars, pubs and restaurants, I'm told, have toilets."
I'm sorry to see so much hatred toward the homeless. Do you see lots of homeless people in bars ordering $6 drinks? No. College kids, perhaps; and yes they pee in alleys after closing sometimes.
In the US we have liquor stores where people carry out bottles of far more affordable liquids. They rarely allow use of toilets. Yes, we have lots of homeless who drink, but we have many more who do not drink. Many who don't do drugs. Many who are simply way down on their luck or need medical attention.
Even sober people have to pee; and those areas where homeless people (men, women and children) end up won't offer a proper facility. Don't be an asshole- homeless people often have no other option.