What a narrow minded way of looking at things. Just because a word doesn't fit 100%, doesn't mean we shouldn't use it if the main idea is there.
"You’re not compelled to offer your services to any particular employer."
But you are compelled to offer your services to an employer, whose ways of working are almost all similar to each other. And it's not like you have infinite choice.
Is it really a choice to move alone somewhere else just to find a decent employer, but sacrifice friends, family, and so on?
Is it really a choice not to work and become homeless, a social outcast?
Is it really a choice to be an entrepreneur, in such a competitive environment that most startups fail, and you need considerable savings to sustain yourself in case of bad times?
Is it really a choice to find such a unicorn of employer that fits a modern day humans needs for privacy, sense of autonomy, sense of progression, good work-life-balance, good compensation, good responsible manager who doesn't micromanage (...), when most employers (have to) follow the same corporativistic mindset to get as most profits as possible out of employees in order to survive in an extremely competitive enviornment?
Is there really a choice when you have children to take care of, a mortgage and are just too tired or barely have any time whatsoever to look for jobs or invest time into your own startup?
Should I continue?
Where is the choice? Where is it?
People are not bound by physical means with the threat of death. Sure. But if you can't see other more subtle and equally powerful binds, then you're blind.
So yes, this is the modern equivalent slavery, in short - modern slavery - and please you stop.