It's interesting. Here in the US, the people I know who are single are almost universally on prepay, PAYG, or a la carte plans, and just buy our phones outright, because contract pricing works out severely in the carrier's favor. Meanwhile, those with families tend just as strongly toward family-plan contracts which come with a phone per person old enough to need one. I haven't sat down to characterize it in detail, but there seems to be an inflection point in line count past which contract pricing starts to make the most sense.