Tech billionaire Elon Musk took a swing at Apple, siding with “Fortnite” maker Epic Games in its fight against the tech giant’s App Store policies that take a standard 30% cut of payment transactions.

“Apple app store fees are a de facto global tax on the Internet. Epic is right,” Musk, the CEO of Tesla and SpaceX, wrote on Twitter.

Shortly after Musk posted the tweet, Epic CEO Tim Sweeney, a longtime critic of Apple’s App Store, weighed in with a new warning that the 30% “Apple Tax” is “far more pernicious than many realize.”

“‘It only applies to digital goods accessible on iOS’, they say — but in the future all physical goods will have a digital presence, and Apple will tax and gatekeep world commerce,” Sweeney tweeted Friday. “Apple must be stopped.”

Musk later continued his commentary. “Normally, competitive pressure would force Apple to lower fees, but Apple & Android have a duopoly on phones. When interface familiarity is taken into account, it’s basically a monopoly,” he tweeted. “The effective 30% sales tax Apple charges is hidden from users or there would be an outcry.”

Reps for Apple didn’t respond to a request for comment.

Last summer Epic sued Apple over the 30% commission on in-app purchases and its policy that bars developers from using outside payment methods. The lawsuit was precipitated by Apple kicking “Fortnite” off the App Store, after Epic tried to offer a 20% discount to in-game currency for customers using direct payment. The case went to trial this spring, and a judge is expected to issue a ruling as soon as next month. (Epic also has sued Google over the same issue, as it applies to the Google Play store, a case that remains pending; “Fortnite” also has been booted from Google Play.)

In 2020, consumers worldwide spent $72.3 billion in the Apple App Store, up 30% year over year, according to estimates by research firm Sensor Tower. For the sake of comparison, in 2019 — before COVID shut down theaters for much of 2020 — global movie box-office grosses were estimated to be $42.5 billion (vs. the App Store’s $55.5 billion take that year).

Meanwhile, a new book, “Power Play: Tesla, Elon Musk and the Bet of the Century” by Wall Street Journal reporter Tim Higgins, claims that Apple CEO Tim Cook had once floated the possibility that Apple acquire Tesla. According to the book, citing a “former aide” to Musk, in a 2016 call with Cook, Musk demanded that he become the CEO of Apple if the company bought Tesla — to which Cook supposedly responded, “Fuck you,” and hung up.

On Friday, Musk said such a conversation never took place. “Cook & I have never spoken or written to each other ever,” he tweeted. “There was a point where I requested to meet with Cook to talk about Apple buying Tesla. There were no conditions of acquisition proposed whatsoever. He refused to meet.” Musk added, “Tesla was worth about 6% of today’s value.”