Zip line also works because it’s for rural areas that don’t have a good road network, in the US driving would almost certainly be faster.

I imagine it depends on the size of delivery. Even with extremely good roads, zipline would probably be faster (I can't imagine that flying in a straight line is _ever_ slower than driving), just lower bandwidth. Single small package? Zipline is probably much faster. Many and/or large packages? Driving is almost certainly faster. Good roads don't change this basic fact, they just change the break even point.