Using mechanical locks and keys would do it. Even just on one door.
Regular cars have the same problem if you accidentally lock your keys in the car with the kid though.
Regular cars have the same problem if you accidentally lock your keys in the car with the kid though.
Unless the kid press the 'lock doors button' by the driver seat.
There actually aren't! Modern cars are surprisingly good at avoiding this. You can't even lock the doors while they are open. The trunk is the only opportunity for that accident.