The problem I have with in-app purchases with kids, is that it's very vague and open ended, and it's getting promoted to my kids. There's no guarantee that pricing will be fair for future content or features. I prefer the initial expense over the lack of transparency. I also prefer the family sharing standard with Apple's Arcade... I can't just pay for an in-app purchase for one of my kids and not the other(s), or there'll be hell to pay.

That's just me though. I'm very happy with Arcade and being able to keep them away from ads / in-app purchases very easily through it.