20-year-old fresh uni graduates or government employees make 30-40k pounds.

Seasoned competent devs easily earn twice as much -- or three times as much if they are contracting, or four times as much if they are good enough to hack it in the well-paying industries (bigTech or finance).

Yes but high end (financial industry and top MNCs) and contract jobs can pay 3-4x more than that. So when you are a good developer and are either from Europe or looking to relocate to Europe, London and Zurich are two top places you should concentrate your job hunt on.

You'll also make good money in Bern, Basel, Lausanne, and Geneva. It isn't just Zurich, the French part is good also.

Entry-level developers with a couple of years experience, perhaps. Not the case for senior developers (more like 60-90k), and getting six figures GBP is not difficult if you're working in finance.