These efforts are being pushed by car dealership groups who apply pressure on legislatures to block anything that reduces the need to bring cars in for servicing or other efforts for manufacturers to sells directly to customers (aka Tesla).
Computer networks are rarely hacked. I'm sure exposing millions of computerized drivetrains to remote upgrade will seem like a great idea in retrospect.
If a government can't force a software backdoor into vehicles, how are they going to stop the next trucker protest from blocking roads or effecting political change?