It's partly the war dividend. Auto industry got well established prior to WW2, around the turn of the century. WW2 and the aftermath changed everything in Europe:
- Much of the continent was a hotbed of dictatorships and extremists well into the late 20th century. Large parts were locked behind the iron curtain; skilled but poor. No way for them to compete. Spain and Greece were dictatorships until ~1975. Italy experienced continuous political instability post-war and arguably still does. Germany was split in two with a giant razorwire wall down the middle. This situation is not conducive to establishing new successful companies.
- Netherlands and Norway became (to some extent) petro states.
- The British population had been subjected to years of wartime propaganda in which all government failures were covered up, so naturally concluded that governments must be pretty great at running things. Even now, previously unknown wartime disasters are still being declassified, one stopped being secret only a few years ago. The British economy became steadily more socialist from the 1940s to the 1980s, being changed only when the economy was on the brink of collapse and Thatcher came in. During the 1970s when HP and Intel were establishing themselves in Silicon Valley the UK government was being toppled by openly communist unions, there were rotating power outages, 3 day weeks, trash piling on the streets, an IMF bailout. Thatcher righted the ship but not before the UK lost most of its heavy industry including its auto industry to militant unionism, along with the drive to set up new industries. Even when a nascent domestic computing industry developed it was partly driven by the BBC wanting to educate kids, and came way late compared to the Valley firms who were by then already large and powerful.
- Europe decided that the best way to avoid a repeat of the war was to unify under a single government, but the form of that government was heavily influenced by the French and their love of protectionist big government subsidies and tariffs. That shapes everything and the EU doesn't hesitate to do things that are blatantly anti-industry or anti-innovation if they think it will advance their agenda of further "integration" i.e. movement of power away from national governments towards the EU institutions. That always takes priority. The US government doesn't have the same goal of abolishing the individual states, so Congress and the Supreme Court often rule in ways that enable local divergence and policy innovation. The EU in contrast sees those things as problems to be solved, not opportunities or constitutional rights.
- Elitist distrust of the population is sadly a long term feature of European culture. After the war Germany decided it needed strong anti-nazi/anti-holocaust speech related laws. Partly as a consequence Europe doesn't have the first amendment or strong free speech culture, and frequently doesn't have any concept of fair use in copyright law, but large parts of Silicon Valley since 2000 aren't really possible without these things. The animating values of early Facebook, Google, Twitter etc are populist in nature and these companies turn towards widespread speech control only came very recently in the grand scheme of things.
And a non-war factor: in some countries an pervasive problem with cultural elitism in which American things are crass and commercial, unlike the refined reasonableness of all things Euro. It's not true so causes people to search around for talking points to try and prop it up. In the tech world this is often privacy and you see the results in the article, where the author interprets criticism of a privacy focused OS nobody cares about (iOS and Android privacy is good enough) as a criticism of making a "European" phone OS.