I've found out in Garry's Mod that if you enter a vehicle using Player:EnterVehicle, you'll be able to drive them as intended, and not just get stuck inside (this includes prop_vehicle_apc). Do we have a similar thing in SourceMod, to force a player inside vehicle? Maybe in that way, we could get vehicles to work. I think the problem is because there's something missing when we simply +use vehicles.
https://www.youtube.com/embed/uLRWiLYjBCU
We have inputs like
EnterVehicle / ExitVehicle, but they are only present in prop_vehicle_prisoner_pod.