

It’s that, plus other factors. The regulations are more lenient, it’s easier to get a more efficient engine in with more mass to work with, it’s easier to pass safety ranking checks, and it’s easier to put comfort features in that consumers want.
Putting a large crumple zone on a compact isn’t as easy as putting one on a giant truck.
(Note this isn’t saying big cars are more or proportionally more efficient , but that the efficiency advances they’ve made over the years are easier to implement in a large engine)



Knowing how.
All routers are just Linux computers managing slightly better than average network cards. (Home routers, obviously. Beefy carrier hardware is different).
A basic setup is essentially installing Linux and then running a handful of commands for packet forwarding. The figuring out how to do it without wifi crashing will take longer because that software is wonky.