I guess you could make the argument that there are vulnerable adults that can’t control their spending

It's not an argument, it's a fact. Just like the mainline gambling industry, IAP relies on this exploitation for a huge chunk of their revenue.

https://twitter.com/Doomlaser/status/497627529524809729

There's even terminology for them, "whales". The psychological manipulation used to entice them is essentially a science perfected by the industry.

https://www.adweek.com/digital/infographic-whales-account-for-70-of-in-app-purchase-revenue/

Apple obviouslty knows this, because its a massive chunk of their store revenue that they don't want to disappear as it will affect AAPL's stock price. Again, this subscription service is a great thing to do