i thought UK already ruled that android apps must run on iOS.

Banning apps that linked sales out of app is what they already did, but that was ruled to be anti-competitive. Then they allowed it, but with an added 27% fee for whatever was purchased through the link (banning if you didn't pay the fee), which was also found to be anti-competitive and a attempt to avoid having to comply with the first ruling.

Charging for bandwidth of app downloads and updates would equate to pennies (relatively). It's not worth it. And would probably be deemed anti-competitive in the future anyway if they didn't also allow 3rd party app stores / installs (like in the EU).

Full context:

"In stark contrast to Apple’s initial in-court testimony, contemporaneous business documents reveal that Apple knew exactly what it was doing and at every turn chose the most anticompetitive option. To hide the truth, Vice-President of Finance, Alex Roman, outright lied under oath. Internally, Phillip Schiller had advocated that Apple comply with the Injunction, but Tim Cook ignored Schiller and instead allowed Chief Financial Officer Luca Maestri and his finance team to convince him otherwise. Cook chose poorly. The real evidence, detailed herein more than meets the clear and convincing standard to find a violation. The Court refers the matter to the United States Attorney for the Northern District of California to investigate whether criminal contempt proceedings are appropriate."

I hope this guy gets hit with the full extent of the law. Not because I think he is a bad person, but because allowing individuals to be sheltered by corporations is at the core of why corps do illegal or legally grey things.