I think it's a very individual thing. Some courses are incredibly demanding, some families simply couldn't afford to keep a child at uni if they didn't earn anything, some students could do with the added responsibility, some students (oooh yes! lecturer speaking here!) could do with spending more time on their studies. Also, some students are good at living on lentil soup and socialising over a shared tea bag, others want a slightly more costly life.
I only worked in the summers, and then as a volunteer abroad, but was able to do evening courses at university level at the same time as doing my standard undergrad programme, meaning I basically ended up with two BA's instead of one. While the paper qualifications may not have made that much difference, the skills I learned have been essential for my later career. I was very good at living cheaply, which was another good skill to learn.
Not everybody who makes a different choice is either an uncaring parent or a lazy immature young person who will end up without life skills.