You don't get government unemployment benefits in the UK if you have >16k in savings (i.e. most programmers, presumably)
Generally uk dev pay is very bad compared to US or even other Europe.
Contract work used to be basically the only way to make good money but this has now been nobbled. Not a good city to work in.
As a result permie developers generally don't have a huge amount of a savings.
Moved to New York following Brexit, now making literally twice that. (Paying twice that for housing, too, but my housing is more like 15 minutes from work instead of 60 and I have a real subway option instead of putting up with Southern Rail and the strikes.)
This isn't true. You'll get new style JSA for 6 months [1] pending you have contributed NI for the past 2/3 years which almost all will have.
https://www.gov.uk/jobseekers-allowance/eligibility
You're talking about universal credit which yes you won't qualify for with greater than 16k savings (pension savings or HTB ISA are however are excluded).