[Cederfjard]

...but they can have zero time to find another job because of being beholden to their job at Walmart, and to the other job?

You're saying they should keep the Walmart job and get rid of the other, and spend the time freed up searching for one that's full time and paid enough to replace both, right? But if you can't support yourself and your dependants on the Walmart job alone, then that's risky.

[soperj]

if they have the other job already, then they clearly had time. I'm not saying they should do anything. I'm saying it doesn't make sense that you can be beholden to a job because of too many hours, and have reduced hours. It's one or the other.

[astrange]

This is covered by search theory in economics. (economists do not use "supply and demand" for jobs, rather they consider things like search time and monopsony power.)