A lot of food containers are impenetrable because of the 'tampering' scares we had a while ago. I often have to ask my son to open the 'push and squeeze' type bottles of bleach, etc.
My GD has a part-time supermarket job. She says that they often find partly-eaten items tucked away on shelves, even things which were well-packaged.
I choose unpackaged fruit and veg, when possible, and have to stop the till operator from putting it in a plastic bag after she has weighed it.
I buy large bottles of liquid bath soap to top up my hand-wash and shower bottles because I can't tell the difference, it avoids throwing away so many bottles, and it is much cheaper, too.
Gaps under/over toilet doors are there to provide access if someone is taken ill inside.
My 'unanswerable' is - how the hell do fieldmice get into my house? I know that they can creep through the tiniest of spaces, but they have got me stumped! They are such cute little things, and i would never hurt one, but I don't want them in the house. Luckily, I have an excellent mouse-catching method involving a mesh wastepaper basket, a pen, and a ball of string.