I think this is also happening in USA long term, lots of "low income" americans who are knowledgeable of navigating welfare programs earn more than middle class workers if you factor in their entitlements.
That said, the US has a different problem. People saving money and flying to cheaper countries instead of working in the US.
As much as Americans think of the UK as a sort of second status foreign overseas territory, and as much as the UK think they're an extra special independent peanut, they're just as much a part of the European pay and expense scheme as anybody else in the mainland is.
Globally, tech workers are worth $40-95k USD. It sucks, but that's what it is.
Maybe for the average pay, but for outliers on the high end, the ceiling is higher in London than what you can make in most other Mainland capitals.
A German guy I know maxed out his TC locally then doubled it when moving to London as nobody in Germany would pay anywhere near that.