I totally agree with you on the general dynamics, but would add govt regulation as another potential balancer. The govt can require things like breaks, overtime pay, and safety conditions that would otherwise have to be negotiated (often unsuccessfully) by employees.
Also, providing a stronger economic safety net gives employees more bargaining power, since it decreases their downside risk.
Small note on this: Companies, especially large companies, spend an exorbant amount of money on lobbying lawmakers. That lobbying money works hard to limit workers' (and consumers', and competitions') rights.
And ultimately, it's not the government alone which got us breaks, overtime pay, and safety conditions - it was the unions using their dues to push the government for those things.
I almost mentioned regulations but didn't for this reason. It would be nice if the government actually put individuals above corporations; but at least here in the USA the situation has been clear for decades... or forever?
Also, providing a stronger economic safety net gives employees more bargaining power, since it decreases their downside risk.