My old next door neighbor had a compost toilet and I didn't notice any smell, even inside of it. I also stayed at an AirBnb with one that didn't smell. I'm sure they can smell awful but it certainly depends.
I imagine it's similar to a yard waste compost pile. If it's not done right the smell can get pretty bad, but a proper one should have little to no problem with smell.
Anecdotes are not why the regulation would exist. The majority of people can do things the right way, but it's always the outliers and bad (lazy?) actors for which the regulation needs to exist for.
I imagine it's similar to a yard waste compost pile. If it's not done right the smell can get pretty bad, but a proper one should have little to no problem with smell.