Originally Posted by Chen
While it does cost more monetarily, you need to look at the opportunity cost as well. Your roommate seems to value their free time more than you do (in a monetary sense) and hence accepts the added expense of continually buying things rather than the alternative of using up free time and less money. Compromise would probably be the best here. Sure buy some disposable stuff but also show them that some things are quick and easy to clean (or whatever) and that it is worthwhile to have permanent things in those situations.
Granted, we don't really know what disposable things we're talking about here, as this could include a scenario where this person is throwing away metal flatware after dirtying it up because they're too lazy to put it in the dish washer or do dishes. Ridiculous, I know, and I'd say it was strawmanning if I hadn't run into it before.