John Boy specifically mentions the HOTs doing community work:
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The implication is that the HOTs are doing the same sort of "work" the DIKs do when we send them to earn money in the mansion mini-game. It just happens offscreen because no one cares when the HOTs to boring stuff fully clothed.
But it's only your assertion that they must be getting mana from heaven. We know Bella has a job because it's plot relevant. If Sage or one of the minor characters earned their pocket money doing minimum wage work, we'd probably only know about it if we stumbled upon them working (the way we did with Beth).
Maya is the only case where the lack of a job is an actual oversight, because we KNOW she has a pressing need for money yet the topic of earning it through a job has never come up (despite the MC/Josy supposedly wanting to help her). For all the other characters, the only ones with a pressing need for money were the DIKs, and we see them start working once the MC convinces them to stand on their own two feet.
It goes both ways. We shouldn't be afraid to criticize the story for its shortcomings, but we don't need to castigate it for flaws that can be easily explained away in game.