Intuitive Design using Colour

My mam and I both have Hetty and Henry vaccuum cleaners. Hetty has been part of my life for three or so years and when mam needed to buy a new hoover, I had no hesitation in recommending the Numac family to her.

I noticed that everytime my mam went to turn off her Henry, that she hit the "hi power" button instead of the on/off switch.

This puzzled me. I never got this wrong. We investigated...

On my cleaner, the on/off switch is green and the hi-power switch is red - this must be the intuitive colour for operation.

Which one would you go for to switch it on/off?
Another example... I remember getting a new bank card and noticing that almost everytime I used it, I inserted it at the wrong end... whereas, this had never happened with my previous card.

Unfortunately I can't remember exactly which end I inserted first, but I think it was blue!