the urge to buy goes down if the subscription is cheap enough ($.99 songs versus $12 a spotify subsscription) but having been through my fair share of attempting contract cancellations this isn't surprising.
My understanding is games with microtransactions optimise for "whales", people who spend inordinate amounts of money. While the majority of users don't pay anything, or at most very little.
My mental image of it is looking at Apple when the iPhone was 2 or 3 years old, and today's Apple: its current size dwarfs the Apple of back in the days, but it wasn't some small also-ran company, it's impact on the whole industry was still pretty big.
AppsFlyer's data on this was interesting, while not straightforward to interpret from our angle.
https://www.appsflyer.com/resources/reports/app-marketing-mo...
If somebody has never purchased an app, setting up payments in the app might be seen as “too much work, especially just for this one app”. But once you get the payments in there, each subsequent 0.99 payment is painless
I mostly share your conclusion, but I think there is a specific twist: most people will pay for on the spot transactions.
We see it in spades for games: in-app purchases and season passes have a lower barrier of acceptance. I assume buying stones to unlock a character must be thought at the same level as buying coffee, as just a one-time purchase that doesn't require further calculations.