The more interesting answer in my mind is that Jonathan does try to find a job when he gets to Cali (maybe even gets one lined up) and then goes home and tells his family and Joyce gets really upset about it, prompting him to quit shortly after. I kind of think that when Joyce herself is doing a little better (financially, mentally, all of it) she becomes more aware of just how much she's leaned on and relied upon Jonathan, and starts feeling super guilty about it. So her solution is to "fix it" by alleviating him of all responsibilities (that is, until the next time she needs him, at which point it goes without question or thought that he's going to be there waiting; e.g., leaving him to watch the kids when she goes off to find Hopper).

This guilt results in various, short-lived spurts throughout the years where she suddenly becomes really insistent on Jonathan "being a normal teen" to try to make up for parentifying him the rest of the time. But what she never realizes is that this back-and-forth is actually more harmful to him than it is helpful. So when he tells her in Cali he's got a new job and is starting on Monday, she feels really caught off guard and devastated. He doesn't need to help her with the bills here! He can just be a teenager!

She sits him down and tells him she doesn't want him to work here. She wants him to focus on his college applications and enjoying his senior year. Jonathan thinks this is ridiculous, because he already isn't enjoying his senior year, and he certainly isn't likely to without Nancy. Not to mention that he keeps pushing applications down the line because he doesn't know what to do about them and he can't tell his mom or Nancy that he's already resigned himself to going to community college and forgetting Emerson (...and NYU). Working, however, is something he can do that is familiar and makes him feel useful and will be a way to pay for college. And he likes Argyle, so working at Surfer Boy would be tons better than any of the shitty jobs he's had before. He wants to work. But he can tell that Joyce is upset and wants him to (at least to pretend to) be happy here. And he hates when Joyce is upset and he's the cause. So he decides his mom needs him to not work more than he needs to work. It's another version of self-sacrificing for his family's benefit above his own. And it ultimately backfires big time, because it gives him wayyy too much time alone with his thoughts, working himself into a spiral that Joyce doesn't even notice.

but CURT HOWLS IN IT TOO?