Not by "nature", but the asymmetry is fundamental to the relationship: one entity provides a service the other pays for it.
Now the specific consequences of that fundamental asymmetry can be changed by political activism, but not the fundamental asymmetry itself. Unless you are going to start paying companies to employ you, whatever that actually means.
> Whatever that relationship is now in the US,
As I explained, the behaviour discussed would just as much get you fired in my native Germany, which is one of the most employee-friendly places around. So unlike what you are trying to imply, that this is a very specific point in the spectrum of possible relationships, it pretty much spans that entire spectrum.
> crying foul is legitimate
Nope, except for in the most legalistic sense: sure you can cry foul. Just don't be surprised if people aren't sympathetic and instead laugh at you. So basically crying foul will not be effective in those circumstances.
If you threaten to quit as a bluff in order to get your demands met, don't be surprised if the other party calls your bluff [and in many sense they have to call your bluff. If you don't understand that...well try to figure it out].
If it wasn't a bluff, then why are you complaining?
> Google does it all the time
How does Google doing something legitimise it?!? They deserve all the scorn they get when they do it.
Of course this isn't a symmetric relationship, but its nature, and even its legal nature, isn't ordained by nature, but is a result of political activism, and differs over time and place. Whatever that relationship is now in the US, it is clearly something that is as temporary as it's always been, and everyone constantly aims to change it. Google's executive and board are much bigger political activists than this group of employees, but they all seek to change the power balance.
> don't be surprised (and cry foul) if you are terminated.
You might not be surprised but crying foul is legitimate. Google does it all the time when it doesn't like various laws and tries to put political pressure to have them changed.