What a weird take to defend tech salaries in Spain, I'd love to move but the very top salaries for my level cap around 80-90k EUR so it'd be quite a big drop even compared to the UK
Where do you read a defense of anything? This is not a "weird take", just a statement of a fact (may it be true or false): that the average is ~40k and not ~15k (it is currently illegal to pay less than 15.876 euros per year).
But be aware that the London salaries upper tail is wider, possibly brought up by the quant firms (which are a different kind of company than most are accustomed)
levels.fyi gives 112kE as the median and 200kE/90% for London vs around 60kE for the median and 90kE/90% (pretax for both)