OK - I know your first thought - I am being U. Bear with me.
On the way back from playgroup today I stopped at a village shop to use the cashpoint. The parking spaces are directly along the outside wall, the cashpoint is about twelve paces away but just around the corner of the building. Owing to a) the fact that baby had just finally gone to sleep and b) the fact that the two cars either side were parked so badly I could barely get my doors open, I decided to leave baby in the car. I knew there was no queue for the machine, and I only wanted to get some cash. (ie. not top up my phone, or check my balance, or nip into the shop for anything.. etc). I was around the corner almost certainly less than a minute.
On my return, TWO people had a go at me. One just said 'it was dangerous' and one said 'someone could have snatched baby through the window'. (The front window was slightly less than half open, the back window next to the car seat was closed).
So go on Mumsnet - how was I unreasonable? Do normal people actually believe the world is filled with very speedy baby-stealing contortionists? I drove away feeling pretty confused, and quite upset really.