Oh, one more story about my flights. This mom was flying with her four little kids. Incredibly well behaved. They had just spend 3 months in Jordan with the dad's family (he had already flown home to work).
Anyway, here is the point:
She wanted to switch seats with another passenger so she could sit on the aisle in between her kids. So rather than ask first, she sat in his seat before he got there and when he came by she pointed to her assigned seat and said "That's my seat. I would like to sit next to my kids, if that's OK." Notice there is no question mark on the sentence. She didn't exactly ask.
Then when he was out of earshot she explained to her 10 year old daughter that this is how you get ahead in life. You don't ask permission you just tell people what you want and make them force the issue if they disagree. Most people are relatively passive and won't do it, even if they want to. If you ask, they may say no, but this way they can't do it.
She is absolutely right that this works. This is a way to use people's tendencies to leave defaults as they are to your advantage. You can get what you want a lot this way. But is it polite? Is it civil? Is it the way we want to teach our kids? I always joke with my students that Human Factors can be used for good and for evil. I think teaching this lesson to a ten-year old is an example of the latter.