That's not what that means at all. Apps pay for it by Apple's commission on download fees, subscriptions, and IAP. Apple is actually more lenient here than most as they allow cross platform wallets and subscriptions for free - not all stores do that.
Anyway, what is true is that most apps don't pay very much. They aren't successful. It's a small number of really big apps make enough that, through the commission, they not only pay for all the ones that don't make anything for anybody, but also turn Apple a rather tidy profit. Spotify, a big app, doesn't want to pay the commission anymore. They have the size and reach to have their own payment processing system and want to use it keep more of the profits. To be fair they have to compete against Apple's own music subscription service. So either way Apple wins, which they understandably chafe at. What's right or just is a different question. Spotify is not wrong that competing in your own walled garden is ... at least unseemly and should be looked at.
However, as I alluded to above, Apple is very much representative of what all walled gardens have always been and is actually better than most. In many ways, Spotify is singling out Apple rather than the other way around. So Spotify in asking for "narrowly tailored" legislation (ie targeting Apple specifically - which btw is unconstitutional) is being disingenuous as to how the industry at large is actually shaped.