Apple and Alphabet’s Google are two of the world’s most profitable companies, and their app marketplaces are among their most profitable endeavours: according to analysts, Apple’s App Store takes in more than $20 billion a year with a profit margin above 75 per cent. Now such practices are coming under increasing scrutiny. US senators and European regulators have griped about the “gatekeeper control” that Apple and Google have with their mobile operating systems. South Korea has moved to become the first country to impose curbs on the companies’ app marketplaces. And a US judge has ordered Apple to make sweeping