And if battery prices continue to decline, electric "motorcycles" (i.e. 3-wheeled cars) with low maintenance costs will be available for similar prices.
First you'd need enough customer traffic to fill the vehicle. There is no point in buying a vehicle that can serve 12 customers if you never get more than 4 at once.
Space to park doesn't seem like a huge problem when they're making deliveries. The mail truck is bigger than these things. Buildings with tight parking commonly have a loading zone or a space with a 15 minute limit specifically for deliveries, and it's big enough for a light truck.
The people making deliveries are doing unskilled labor. It was never expected to pay well. The question is if it can work at all.
As far as paying well, I don't think that was ever really expected, but these companies just seem like losers for all but those who managed to cash out in the IPO.
There are a lot of potential industries that have to start out like this.
Suppose you have a downtown where there are a dozen restaurants within a few blocks of each other, and then customers in a residential area on the other side of town. If you try to hire someone to go pick up the food for one person and deliver it to one customer on the other side of town, it's totally hopeless and you'll never make any money.
But if you could get the same driver to pick up meals for a dozen people at once and then deliver them to customers who all live near each other, now you have a chance of turning a profit. That's a chicken and egg problem, because the first customer isn't going to pay the full price of the trip, so you have no first customer and never get enough business going to reach the level of efficiency required.
Now suppose they operate by burning VC money for a while until they get enough usage to turn a profit.