Nice thing about drones is they're unlikely to kill anyone if they crash, and they're not sharing the roads with cars in the first place.
In some places, bikes are first-class citizens of the road, but in other places they're very much not respected and riding one is tantamount to suicide. Every single cyclist I know, when they meet another cyclist, immediately asks about gnarliest injuries and they compare scars like dogs sniffing each other's butts. And in the past 20 years I've lost more friends to cycling fatalities than any other cause of death.
E-bike courriers are probably better still but drones are probably faster if you can make them work.
A lot depends on the delivery pattern, of course.