Many junior developer roles in London will pay 50k. Some finance ones will pay 75k or more.
600k USD / 450k GBP is also definitely reachable for a senior developer at team leader level or comparable.
Also at this level you enter into a negotiation with the business stakeholders, compensation package is tailored to each profile and opportunity.
Let’s forget that salaries in Europe are ridiculously low to focus on the handful of people who might get an extraordinary position - still paid less than an equivalent one in North America nevertheless - and pretends its doable and everything is fine.
And that's not even the top salaries, there are also jobs that pay in millions.
You'll also find similar salaries in Amsterdam, Paris, Zurich...
I'm just stating that jobs that pay the same as in the article do exist in Europe, and I don't believe they're as exceptional as you suggest.
There just is a large spectrum of salaries for software engineering, and as we all know, 90% of everything is crud, so of course the median will be much lower.
Back to tech though, there are probably 100 100k roles for every 400k role. So if you start out making 100k in tech, you have to be 1 in 100 to move up to a 400k role.
2009 was also a recession year where it was difficult to find an entry level job at all, at any salary. I went without (software) work for half a year when I was laid off at the end of 2008 and ended up having to relocate for employment.
I'm in my late 30s now and I'm well off by almost every measure (I max out all retirement accounts, I have a six figure brokerage account) - but I'm nowhere near a millionaire or financially independent. I'll need to work another decade best case scenario.
The biggest boost to my savings rate/financial position came from getting married and sharing income/bills with my husband.
If I did it over again I'd pay off my loans slower and put more in my retirement accounts earlier.