Child locks?

Of course, there is no child lock made that can keep John out.  So, long ago we resorted to tying up the cupboard to keep him out.  It's a serious pain to have to untie that thing every time you want to sneak a snack, especially after he has pulled on it so the knot is super tight.  
But, despite years of not being able to beat this system he continues to try.  The problem is now he is strong enough that the cabinets themselves can be beaten:

Not sure what to do about this.  I think I can repair it, but why?  Now that he knows it's possible I'm sure he'll continue to break it.   I'm open to ideas.   I wonder if they have solid steel cabinets?  :)

Maybe you are wondering where I was while this damage was taking place?  Well, I was in the other room steam cleaning the carpet after he intentionally gagged himself and puked.   And, he was gagging himself while I was in the bedroom replacing all the sheets that he pulled of the bed.   And, he pulled the sheets off the bed while I was cleaning up the box of screwdrivers that he dumped on the floor.  See where this is going?

It's getting very close to being a 2 person job to watch him.  One can do it if they are energetic and watch him closely, but if you get behind and have to clean up after one mess, he will stay one step ahead of you with his troublemaking.  

The easiest way to keep him out of trouble is to just take him for drives.  I wonder how many thousands of miles I've driven him around in circles.