“But then isn’t it the case that in some other countries, “liberal arts general education” is supposed to occur in upper high school rather than lower university?”
Not really. In the UK you also specialize for the last two years of high school (A levels). You then do something that interests you at university. But just like the US, if you go to a tippy top university (e.g. Oxbridge) your choice of subject makes very little difference to your subsequent job opportunities. You do need to be numerate (almost all UK graduate interviews involve a challenging numeracy test), but at the top level that’s usually the case even if you did arts subjects from the age of 16 onwards. In fact the classic job for UK graduates (especially in arts subjects) who don’t know what they want to do is to become an accountant - its effectively a general purpose qualification for corporate life, much like a law degree would be in the US, but you get paid to get the qualification.