In a car-hostile/bike-friendly city, they're going to be able to move much faster than a car, so the only downside is that you need to plan shorter routes/return to the base more often. Which probably isn't as big of a drag in a compact city as you'd think.
A cargo bike with a 90x60x60cm box can fit 36 packages assuming a 15x20x30 size (weight will not be the limiting factor for the typical "one piece of electronics and some air" packages). 36 stops with 5 minutes per stop (travel + stopping and delivering the package) is 3 hours.
A cargo bike with a 90x60x60cm box can fit 36 packages assuming a 15x20x30 size (weight will not be the limiting factor for the typical "one piece of electronics and some air" packages). 36 stops with 5 minutes per stop (travel + stopping and delivering the package) is 3 hours.