While I do think that is a great example, it would appear that your peer group might have a self-selection bias for increased security, vs the normal population.

A quick google search leads to multiple articles suggesting that the vast majority of people do not lock their phones.

As to whether they would give you their phones or not is a different question, but I would wager that many (most?) of those who don't lock their phones would also not necessarily care if someone looks at their device, or at the very least do not take measures to prevent others from doing so.