There are some people who are not well educated and they can't get other jobs. So yes, that might be the only job where they can work around limitations on child care or whatever.
Yes wage slavery is a key features of capitalism, and a key incentive for capitalists (the economic class) to oppose reforms to increase the economic security of the working class, as mitigating wage slavery frees employees to demand a greater share of the value produced.
You could say the same about every American living paycheck to paycheck. Are they all slaves?