Anecdote, I know, but of all the 20 odd escorts I've seen over the last year or so, only three were part time. Funnily enough they are all British. Two of them work in data analysis and the third in the Care sector.
Others who revealed a previous career included an au pair and an office gofer.
I think the Guardian is talking bollox (again). A large proportion of their readers are in the State sector as teachers, health professionals, Social Worker types. I reckon this kind of article is clickbait for those readers.