Hi, scary stuff, my son used to do that. My husband reversed the lock for the door, where you need a key to open it to venture outside, also a deadbolt too. It worked well, never had problems after that.
Some use a harness and fasten it together before any car door is open! Some use a stroller to gradually train a child away from stroller use! Some take a companion for car trips so that one person always provides protective supervision, until there is a plan to "fade" the support plan so that eventually a child is self-managing safe transition.
My son runs off to the street when he gets out of the car. He doesnt even bother looking. I keep and keep telling him that he needs to look both ways before crossing or even thinking about running into the streets. He still doesnt get it. Its cery hard but i do explain it to him and keep explain it and i grab his hand and tell him ok now what do u do when we are about to cross the street? He has gotten better with it but sometimes he forgets and i thank god that no car has been passing when he runs off
We put a really funky child lock on both front doors and amped up our locks on our garden gates. We also left the doors outside squeaky so that we can hear when he opens them. He's starting to get strong enough for managing the locks, though, so we'll probably switch to a keypad lock before too long.
Also, the last time Alex ran off, I made him walk back all the way holding my hand, and I walked s-l-o-w-l-y. While we walked, I explained I had to hold his hand because he ran off from me and didn't listen when I called after him. I also walked slowly because I was beat chasing after him! He hasn't done it since.
When my daughter was younger and reception was off I used sign language to make her aware of safety issues. She used to go near the road. I told her over and over through sign language to never run across the street. She'd get hit by a car. It first when she didn't listen I took computer privileges away. It sunk in though. Her life was more important so I never let parental guilt take over on discipline.