The DTs regularly shut each other in the tumble drier. Fortunately the day before they began this peculiar habit the door broke. I was so cross that I would have to pay a fortune to have a minor fault repaired. Once I saw that they could lock themselves in I was glad that it was broken.
Small children have an incredible habit of being where they shouldn't and getting into or out of places/things that they shouldn't.
The chances of this happening are very small. It doesn't mean that we shouldn't be vilgilant but it does mean that we shouldn't become paranoid etc.