The delivery vehicles being used in NYC are almost entirely e-bikes, so the expense is not as big as you might be thinking. It's certainly nothing close to the cost to gig workers for running an Uber car.
Though keep in mind they're throttle e-bikes, so there isn't a lot of actual pedaling going on. And as far as accumulated workplace injuries go, merely riding a bike is pretty easy compared to a lot of blue collar work. No, I think what'd get you here is the crashes.
Because anywhere that has any air pollution, you'll ingest more when you're breathing harder and have no air filter.