Morality or opportunity

I have always believed that the quote "Tell me how you measure me, and I will tell you how I will behave" was a truism but more and more I am beginning to believe it is not morality but opportunity, or rather the removal of it, that keeps people in line. For example, if you leave a £5 note on the pavement some people will pick it up an pocket it (stealing), some will walk past (avoiding any moral decision) and some hand it in to the police (very few I fear). However, if the £5 note had not been there (no opportunity) no one would have had their morality tested.

What do you think?

My thoughts have so far covered the poor care in some hospitals where paperwork was put first, the behaviour of some towards benefits and politicians abusing their expenses.