I do not drive with day care children. I used to have van but even then, for family not day care.
It means having right age seats or getting parent to leave car seat which is space using. It means having in date seats as seats expire now. It means having extra insurance. Lots of liability with seats, car reliability, enough insurance, children mixing with large public group, ability to supervise properly, parents signing disclaimers/liability releases.
I don not run errands in my work day. And play dates, play cafes are tricky to watch 6 properly. We have wagon and walk but not in car.

