The biggest reasons I see is that Europe is still a collection nation states whit each having it's own language, culture, laws and needs, EU hasn't removed those (yet, god forbid). There really is no single market for many services like there is in the US, in Europe you have to develop and sometimes apply for permits and licenses for each country even with the EU, since EU usually regulates retroactively not so much proactively.

The second is that there is nothing like the US federal government or military that could fund and/or bootstrap tech companies with contracts. Like google, SpaceX and Microsoft have both benefited massively from taking lucrative contracts from military government and US intelligence agencies in the past. Those allowed them to grow and consolidate first cover the US and then springboard themselves global.

Do you really want a European Google?

I always had the impression that the free software idea had a stronger presence in Europe (and, generally, non-Anglo areas) and have generally chalked that up to the fact that the ambiguity of free (as in freedom)/free (as in beer) largely does not exist outside of English. Note that "open" is every bit as ambiguous as "free" here - i've had way too many arguments with people who thought "open" just means you can look at the source code (imagine thinking that a store was "open" just because you can look through the window and see products).

However IMO the author goes a bit too far in presenting free software seemingly as some sort of uniquely European concept - he seems to suggest that the creation of Linux came about entirely out of thin air, and almost reads to me like Linus Torvalds originated the idea of copyleft - with no mention whatsoever of the American GNU project upon whose shoulders he stands. Allegedly he was inspired by a talk Richard Stallman gave at his university in 1990.

https://www.oreilly.com/openbook/freedom/ch09.html

Edit: Git also did not come out of thin air, Linux developers were using a proprietary (American) VCS in the beginning, under a gratis license specifically granted for Linux development. The Australian developer Andrew Tridgell is arguably the person most responsible for inciting the development of git, as the proprietary VCS developer withdrew the gratis licenses once he developed a free tool which could interoperate with the proprietary servers.

https://www.gnu.org/philosophy/mcvoy.html

(That proprietary tool is now licensed under the Apache 2.0 license, but as far as I know no one uses it anymore)

SearXNG exists and Qwant is one search engine that I know of.

All this nice opensource code still is executed on hardware owned (Intellectual Property/IP) by AMD/Intel/Qualcomm/NVIDIA/Apple. Having nice European-Open Source projects is not enough without the hardware layer and standards (instruction sets, drivers), which are owned IP by US cooperation's.

Also one needs to consider cooperation between military-complex/secret-service and big-tech cooperation, which are basically hidden subsidies for the civilian part of the business. And if eu governments do not subsidize their own tech standards similarly they will get out-competed naturally.