They can charge you after you get rescued. Or does that come out as a negligible amount?
But I suspect their actual business model will be to charge for non-emergency messaging, which might just be able to subsidize the emergency use case.
Generally, SAR teams would rather the R continue to stand for Rescue rather than Recovery (of a body).
Outside of the US all bets are off. Plenty of rescue services that charge.
But “iPhone saves man’s life after he fell down a mountain” sounds a whole lot better than “worlds richest company charges man who nearly died $25 to save his life”.