My impression: they don't. I am officially a parttime PhD student (UK), live in another country (need to work, self-employed, which also requires dedication). I sometimes get the feeling that enrolling parttime is interpreted by some as "has loads of money and doesn't need to work".
Sorry, currently bit annoyed, but like you, trying to find solutions. Saw that you hadn't gotten any replies and wanted to let you know that you're not alone in trying to find a way to lead a balanced life and not give up (almost) everything else in life