Even most US devs don’t make $240k USD.
$120k is also an underestimate given that the top tax bracket in the UK is only 45%. If you apply that, you get $132k (Still an underestimate). $132k is roughly in the same ballpark as $155k.
It's not like the difference between the same income in the US and UK is 50%, and even if you were on $120k USD net that's the same as the median gross income of a SWE in the US.
I don't understand where "not that much" is coming from.