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.

Family contracts are a huge savings over individual pay as you go plans.

Not so much, at most you'll save $5 to $10 a line compared to an MVNO. Postpaid carriers primarily make their money by locking you in on plans mis-sized for your needs, does every family member use unlimited data? Rarely.

Equipment protection plans and other similar features are also another profit center to beware of.