Honestly those examples you provided take a lot more skill and effort than most people put into exploitive sex. The consequences of doing those examples “wrong” are far higher, too, e.g. loss of life or limb.

I think a better retort would be that people want professional jobs where their contribution is based on seemingly objective merit. If 50% of your performance is judged by one person in an entirely subjective way, i.e. their satisfaction with sex, it’s not a very well protected job for one thing. Further, the benefit of exploitive sex industries is not having to commit - to be able to switch it up. Tightly coupling your exploitive sex with job positions whose value increases directly with the amount of institutional knowledge retained would not be wise - your turnover or dissatisfaction would be too high. Finally, despite all the efforts of exploitive industries, sex is still a biological function and very personal to many (most?). There are subtle relationships involved in such intimacy despite efforts to avoid it. From a management perspective, there’s a risk to being “friends” with people that work for you, much less having sex with them. I think it would introduce too many opportunities for personal feelings interrupting optimal productivity. Put directly, the integrity of your decision-making ability on behalf of the company would likely be compromised.

Most people have no job protection whatsoever.

Could just as easily argue that providing sexual services increases her job security.

That’s not remotely true for US corporate work. Companies want to protect their investments - progressive discipline policies are set up with the intention of avoiding the liabilities and wastefulness incurred by the hasty decision making of a single individual. Most companies reserve their “at-will” status, but in practice getting fired on the spot for an exception or omission (non-criminal) is pretty rare. Usually there’s a layer or two before outright termination. It took me years to appreciate the fact that my skills and knowledge made me more valuable to a company than a single screw-up could overshadow. Took a lot of stress and anxiety off my shoulders when I did.

This phenomena doesn’t apply to just dangerous work. One should expect any provision in a contract to be the norm. If a contract specifies that work on Saturdays is ok, assume every Saturday that you will work. Adjust your pay requirements to reflect this. Don’t let the other party to convince you that “it’ll only be sometimes” or “just in case”. For the 50% stuff, the real answer is empower the worker and train people to sign 2 different contracts for seemingly unrelated jobs. If that screws them out of benefits, then ask for more money. At the very least, it prevents the low pay for hard labor.

Receptionist + some heavy underground construction at the boring company.

Sounds awesome.

None of those examples seem to have a problem...