Going to get flamed for this but here goes!
In every single job I've been in I've worked with people younger than me who work part time hours. I can't quite get my head around it.
In my previous job I was a retail manager. Most of the staff were young, 20-30, none had kids apart from me and one other lady. We used to have a sheet of overtime shifts up and I used to have to beg staff to work it. These are young people, not studying, none with disabilities that they disclosed to me, most were renting/ house sharing. I never understood why they didn't want to work more hours, get more money for house deposits, travelling etc.
Another job I was an admin assistant and two or three of the other admin were young women, married with no children, who worked three or four days a week. Why?! Even if their husbands earned enough to support them, shouldn't they have worked to save for maternity leave, holidays, nice car etc.
I know money doesn't motivate a lot of people but as a young, childfree person, I would have never thought to apply for a part time job, unless I could be assured there was overtime. If not for financial reasons then just out of boredom, as all my friends would have been working full time.
Currently I work 32 hours due to no afterschool club, my colleague works the same hours. She said to me yesterday she wants to drop a day as she's exhausted. She's 28?! We work in an office together. She moans about not being a homeowner, why not work more hours?
Sorry rant over.