[DoodleDawg]

In the meantime, bosses can just dump more work on their staff, since even the most beleaguered workers are still too afraid to quit.

There's your explanation right there.

[CaptainAmiigaf]

YOUR post explains both the situation and your attitude. You don’t refer to the prospective “employer” but scornfully use the word “bosses”. Employees are not people working and earning a living, but are “beleagured workers”, trapped in a terrible bind so they can feed a family.
I am in dire need to hire a “beleagured worker”, but there are so many like you, I’ll do the work myself.
You can create laws and regulations to harass “awful employers”, but you CANNOT require anyone to become an employer.