Here's the reality. People choose, sometimes, to live aboard a moving vessel - either by land or by sea. These people take an audit of the pros and the cons, and they decide that dumping out a compost toilet once a day (if that) while the coffee is brewing is worth the benefit of living in nature or at a low cost, or whatever their bigger rationale is.
What you are saying is basically: "Oh BROTHER! You thought you'd like to have a dog? Good choice, nimwit, bet you never considered they have to EAT and POOP and be TRAINED." The fact is that most dog owners enjoy the companionship so much that they actually have no problem taking on these chores, because the positive outweighs the negative. Of course no one enjoys picking up dog shit, but it's a price to pay and it has to be done, so most of the time good people who like dogs do it.
Or worse, you get the inconsiderate people who will just unload their toilet into the nearest storm drain and make all vandwellers look bad.
Did you know that in the UK narrowboaters on the canals just dump their grey water into the canal? The canal system in the UK is huge, and their are tens of thousands of people who live on narrowboats year round. Narrowboats are boats narrow enough (5'10") and short enough (max 52' or 72' long) that they can fit through all the locks and bridges.
I also live on the coast, and know many fishermen/lobstermen etc. - do you know where they shit? Not in a "marine toilet" Hang your ass over the edge of the boat and be ready for a round of jokes and pranks by your shipmates. Why? Because dumping your shitter is a giant pain (I feel like a broken record)
So something that's an afterthought in a real home, becomes a weekly, or every other day chore of finding a public toilet, removing your toilet (full of shit and piss) from your van, then dumping shit in said toilet without spilling (not easy) all the while avoiding police/public works employees who would rather you not dump your shit into their facilities. Sounds fun.