Firstly, I see the salaries for *junior* lecturers being in the range £35,000 - £50,000 which is around $48,000 - $66,000 at current exchange rates. So your estimate of $65,000 is more at the top end of this range than in the average.

Note that mid to senior positions, particularly for experienced Science/Tech/Engineering/Medicine (STEM) researchers, would pay far better and also offer more scope for consultancy earnings claw-back. Clearly arts and humanities educators are largely precluded from such salary differentials and I see little scope for academia supported sidelines for them.

While many UK institutions have group health/invalidity/life/childcare/sports/etc benefits, these may vary a lot from one college to another. You would do well to read the fine print of these following an offer.

But to your question as to why - money apart - academics would choose UK over USA positions. 

There are reasons that are specific to the field of study the academic engages in such as:

* UK is the home of English language & literature and a period working and teaching here would be impressive for someone involved in that endeavour. A similar case could be made for those involved in history, archaeology, politics, economics, philosophy, etc research that is centred on or closely related to developments in the UK or even Western Europe.

* In fields that are declining, e.g. metallurgy, there are few local applicants and it has become common for UK universities to recruit such faculty from countries with far bigger mineral/metallurgical industries like USA, Canada, Australia, South Africa or Russia.

* It could happen that the an academic wants to be involved in the research work happening at some UK university department and peer congeniality is worth more - at least for a few years - than salary as they cut their research teeth.

There are also other reasons independent of the academic's field like:

* USA students are quite challenging verbally in class, expect more assignments (plus feedback), take no pomposity and humbug from professors and thrive on continual engagement. Even for those brought up in US, some may not find this as agreeable as the more detached and generalized way of relating to students that is the norm in UK universities. (Of course there are also some UK-born academics who prefer the American way of education.)

* There are loads of foreign faculty in UK universities - perhaps even more so than in USA - so academics who like exotic college social lives will really have a good time.

* Education, health  and social security benefits in UK are better in UK. This is important as an academic's own family reach their mid-teens and become a greater expense.

* Lifestyle and human relationships in the UK suits people who are more reserved and don't want to mix with people purely on the basis of economic status.

* Housing, especially housing in rural villages outside provincial UK cities, is relatively cheap and academic jobs are seen by bank managers as a good basis for a mortgage: fairly secure, many other expenses part-subsidized and promotion almost certain.

* Some people are Anglophiles, Formula 1 enthusiasts, horse racing fans, rugby or soccer screamers, etc and find ample outlet for these passions within UK.

I think that it all comes down to what sort of person you are and what your priorities, both in academia and in the community, are that will guide your decision to work in the UK.

Please don't decide on the basis of some brief summer school experience.