Tunisian female here. The answer is simple for Tunisian women. The highest paying jobs are in Engineering and Medicine and all of the other jobs are miserable. That combined with a free-ish education where you can choose any field, makes the choice obvious.

I personally see the lack of women in STEM in Western countries as a good thing, it means that they are doing well economically and don't have to deal with the tedious STEM education and workload.