It could reasonably be argued that it's for convenience, that one could buy several products in a specific timeframe without having to continuously enter a password, but it's up to the courts to decide these things. Undoubtably, the evidence will be comprised of how much apple profits from f2p purchases, the contractual obligations they haev to the developers, and some kind of scientific proof that argues for the existence of a 15 minute window, say, studies that show most purchases happen at the same time in a single sitting, or buying window.

The lawsuit will likely be upheld. iOS has been a known feeding ground for these f2p apps that target kids, and apple has not done its responsibility in protecting its customers. For example, a 15-minute window is all well and good...when it's at the discretion of the user. The existence of it as a default (if there were an option) is risky.

I think the payout will likely be judged based on how much of an infraction it is. If it was a simple oversight, or argued to be so, plaintiffs might get full refunds plus damages resulting from them (overdraft fees, etc). If it's judged that the decision was a business one, it could be a lot worse.

What parents should / shouldn't do has no bearing on the vileness of predatory marketing practices like this. The knowledge that a lot of parents are slack when it comes to these things should not be a licence to make money off poor parenting skills. Parents need to be protected (or at least not made to suffer excessively) from their own stupidity, not exploited because of it.

This seems to summarize the point neatly enough.