T.F.
My daughter babysits for 3 families regularly.
The families who pay well and respect the sitters keep the good sitters.
My daughter averages $12-$15 per hour CASH and she does not set a rate. She also drives to a job if needed.
Rates vary depending on the area. A rural area is less pay than a larger burb area like we are. $10 is pretty much the average for most teen sitters here.
I do think your daughters were taken advantage of with the 8 kids/4 family night. If that happened to my daughter she would never sit for that family again. She has 1 family with 3 girls that are wild and she refuses to sit for them because they are so much trouble and the dad pays $5/hr for all 3 kids.
Good luck