That is the problem... everyone has a job, often two or three. But they are scared they won't make rent, scared they will get laid off, scared they will need to go to the doctor and fail to show up for work on an on-call day and lose their job.
Scheduling security and overtime threshold are two big frontiers for the American labor movement in the coming years. Just-in-time scheduling is one of the biggest complaints people have, more so even than wages.