Having a relationship with someone at work, especially if there is a power dynamic between you isn't a human right as far as I know..

You can't ban someone from having a relationship. But you certainly can require them to disclose such a conflict of interest to the board.

As a manager of McDonald's?

It is not a human right to have sex with whomever you wish free of restrictions.

It absolutely is for two consenting adults who aren't blood related.

It certainly isn't something for Ronald fucking McDonald to have an opinion about.

No, it isn't.

In the US, most employment is at-will, which means they can fire you for any reason they want except for a list of prohibited reasons.

"Having sex with a direct report" is not on that list of prohibited reasons.

If you can be fired for any reason, then that's it and they can put in the contract that you aren't allowed to drink a glass of water if so be.

But does that make it reasonable for hackers to think that drinking a glass of water is some kind of horrible offence, like some lunatics seem to think about workplace relationships? Which are one of the most common way that people meet and get married.

Having a relationship with someone you have authority over is considered very problematic just about everywhere, in part because the existence of that authority creates problems for consent (among other reasons).

You don't have "authority" over somebody just because you're their boss at work. Only in the military.

Do all of you corporate people also let your employer tell you what you're allowed to eat and drink? Or tell you where you're allowed to be when not on the clock? Maybe tell you what movies you're allowed to go see in the cinema?

Somebody who lets other people take agency over their sexuality or other basic human functions cannot be considered fully human. Why would you trade away that?

They can in fact put in the contract that you aren't allowed to drink a glass of water.

Your remedy for that problem is not to accept that job or to refuse to sign the contract and negotiate.

It is for that reason that no job in the US has that term.