Would You Manage 70 Children and a 15-Ton Vehicle for $18 an Hour?
fivethirtyeight.com
fivethirtyeight.com
Which is to say, maybe all the women who have typically had this skillset and inclination have been pushed into universities, and now "pay more" is $35/hr, not $19/hr.
Add to this that suburban schools of the types often built in recent decades take way more bussing infrastructure, and the driving would be way more stressful in those environments. If you're reading a story about someone idling their car in line for an hour, that's definitely the setting (where I grew up, it only took 10 minutes to bike home from school at child pace, so you'd just do that). So maybe you could put $20/hr and get enough people, but it's also a 40% increase in hours that have to be paid and similar increase in equipment costs.