[mattlondon]

Because other people do it wrong :)

My own mother and of course my mother in law are absolute liabilities with my 5 and 3 year olds. They continually and repeatedly break our rules.

It's not unsafe per se, but it's just high-risk things for no reason apart from what we believe is just willful defiance from the grandparents. E.g. letting them out into the garden with no direct supervision, when there is no physical barrier from them getting into the road etc. "Oh lighten up! It's just a busy street with loads of distracted drivers in 2+ ton vehicles going over the speed limit! What's the problem!"

As a result, they're not usually left alone with the kids unless we can avoid it.

Ultimately if any harm were to come, I want to know that it was my own fault effectively, and not because I suspected that some other adult was not paying enough attention, or could have tried harder/made more effort to stop it, or was deliberately not doing things how I like it to be done. If it was under your own watch or your partner's watch that something bad happened then you can be pretty sure that the harm was unavoidable and not because someone else has other concepts of safety and risk for your offspring.