It happens to me a lot at the dungeon I frequent where everyone knows I'm a switch. When I go outside to smoke, nearly every man there tries to light my cigarette. My take on this phenomenon is that there are truly very few alpha males who are inclined to be responsible for another person. Many of the so-called dominants are really just tops which is why a dom/dom relationship would appeal to them. They're looking for an equal partner in life, and strong women are attractive. That's my 2 cents, anyway.