Oh, sex work has always been 'legitimate work.'
It's just the absolute rock-bottom level of it. A negative respect job. Like being a day/manual laborer is for men (in the eyes of most women). Except it's so super easy to make good money at it, so even those day laborers look down on it.
And women love easy work, and don't ever want to be held accountable for their choices. They don't want to feel bad. As long as they can ignore the shame, it's 'good work.' And they desperately need a level of respect for doing sex work in order to be able to ignore it, and they need to parlay that respect into long term relationships. Both of which they're failing at.
Because it isn't a respect garnering job. It's a job for the desperate, and the lazy.