Apple would then force the with-IAP price to be the same as the without-IAP price so that they get a 30% cut of your rent regardless. You may be underestimating their willingness to tax all economic activity

While this would obviously be harmful to the consumer, I don't see this as plausible.

Amazon was able to achieve this by positioning themselves as the primary distributor of the goods in question. Apple is in no position to leverage a monopoly over fiat transer or housing supply.

With regard to municipal transportation, perhaps they are edging closer with Apple Pay, NFC, Wallet, etc.. but I can't imagine municipalities supporting, or constituents accepting, a tax on their existing taxes.

Of course, maybe Apple.gov is the long game. Hard to say whether that would be better or worse that the status quo..