Hmm, that's probably a good point. NYC residents likely have little use for compost. And having to wheel bales (?) of dried poop out of your flat could get a bit annoying. Then again, presumably they already take out their trash, so maybe it's not totally unfeasible?

It's difficult to fully sterilize the compost, and it's very easy to end up with compost that is full of pathogens and parasites. With millions of people in a small area, I think that alone makes this idea infeasible.

The toilets also don't produce bales of dried poop, the composting only partially completes in the toilet itself--it has to be completed outside in a compost heap.

Also dry composting toilets tend to produce more odors than the average person wants to deal with in their small living space.