I can't remember if it was my eyes playing tricks on me, but last time I went on a XC 170 I saw someone with their laptop plugged in by the door?
I'm not 100% though.
There are sockets by the doors on turbostars, but they're not supposed to be used by passengers.
Voyagers are at every seat, well they certainly were Prior to Arriva reconfiguring them!
People may plug their devices in by the door on a 170 but it'll be totally useless as nothing comes out of them when running and/or not on depot. Someone yesterday complained to me that the plugs weren't working by the door and I quickly explained they ate not for passengers and work fine.