Even before flush toilets, lazy people were a problem. People would toss their night waste out of upper windows and woe betide the unlucky Victorian gentleman walking on the street below!
I've been in a number of third-world countries in our modern times where people just urinate or defecate wherever they feel like. In alleys, on street corners, or in the street itself! These people don't have flush toilets and modern waste treatment, but they don't bother collecting their waste in a sanitary composting manner either.
The problem, as I see it, is one of caring. Most people simply don't care about soil fertility or proper waste disposal
enough to go through the motions. There's no reason why a person living in a suburb couldn't have a composting toilet
bucket set up in their bathroom beside the regular commode and use it instead, then take the bucket down to the backyard to compost it. Your neighbors don't have to know what's in the bucket or the pile if you do it right and the
city government certainly isn't going to send someone to your house to stand over you while you
poop to make sure you do it in the appropriate receptacle.
It's a city problem. In cities you will always find the largest concentration of people who don't care. It's not just a matter of proper education either. They simply don't care. The same resources that
led you and I to the concept of renewable soil fertility and composting human manure are available to them, but they don't care enough to investigate further when the clues light up in front of them.
I'm not sure I'd even want the excrement of a million city dwellers. Have you seen what they eat? I wouldn't
feed that crap to my beautiful compost piles. It's all chemicals and preservatives and probably would kill the pile, just as it's killing the city dwellers.