Call a spade a spade. Not even the mafia extorted businesses for 30%. I'd argue an act of digital eminent domain is in order. Imagine being a store owner and having to give a 30% kickback to your landlord.
well, for one get rid of laws that allow platform manufacturers to control who makes stuff that runs on their platform. (even stronger would be to mandate providing an open api or equivalent, but just getting saying interop trumped the dmca would be a great start). that would fix the issues with xbox, nintendo, playstation and ios immediately. best buy, game stop and steam aren't as bad, they don't have as many reasons they can't be competed against if someone was minded to.
Most shops do have to pay somewhere around 15% of the revenue in rent. In addition to the flat cost, there are tons of commercial leases that charge a percentage of profits on top of that.
well maybe the digital word needs Georgism too. The OP is exactly right, what Apple is doing is nothing else than the digital equivalent of extracting land rents.
If Apple, Google et al want to have control over their digital domains honestly instead of breaking them up let's just socialise the economic rents, or cap it at 2% or whatever.