Well, there is the simple fact that this is a tv show, and I've learned to lower my complaining level about things that don't make sense or couldn't possibly occur. -Off course the writers don't care to explain how Buffy has hot looking clothes, a huge house, and a sister to support, but in no way does she have a salary large enough for any of it.
Maybe Xander helps Buffy out, 'cause he's all successful now with the construction stuff. Here's a better question: How is Willow supporting herself?
Heck, I'm still looking for a better explanation as to why vampires breathe all the time. No more excuses like 'the actors have to breathe' & 'they like to look more human'. Come on!🙄. It's time for them to suck it up, hold their breath, and stop gasping after running! 😛