I think people who used to work 25 hours a week for $9/hr are doing the math and making a decision that it isn't worth working in these jobs anymore for so low pay. It is cheaper to stay home, handle their own child care, and more enjoyable for them to spend more time with their family, etc. Just the cost of work clothing, cost of gas to/from work, etc. is going to eat up a huge chunk of the pay. Many of these folks also used government assistance programs to pay for things like child care, etc.- and there is still a time burden on getting that assistance including paperwork, dealing with a case worker, actually securing the child care, ensuring the child care place is working out okay, pick up/drop off, dealing with the kid being sick more due to all the exposure, etc. I think they are deciding it just isn't worth the $150 a week they may clear after taxes in many states. Let's move them to CA - $13/hr minimum wage. I think they are still just deciding it isn't worth the $280 or so a week they'd clear after taxes in a state like CA, to deal with all of this.
These businesses that rely on low wage part time labor that they jerk around on scheduling and pay few to no benefits, are screwed. They are going to have to get real creative to survive. It is easy to say automation is the answer but it isn't that easy.