Should I be concerned about lack of carseats on field trips?

I have a 3 year old who is ready for pre-school and have enrolled her at two places - Smiles Day School and Lakeshore Children's Center. I really like Lakeshore with the exception that they take many field trips but don't use car seats for the children. It is also further from my house. That alone could be the deciding factor not to go there, since I have two other children, each in a different place. Smiles is nice, but their outdoor play area at the church site is cement and not available to the children in the late afternoon when elementary school age children are also there. They also have a less open feeling in the center as far as choice of activities. My dilemma is whether I should be so concerned about the lack of car seats on field trips. The director says that by law they are not required to put everyone in car seats because it is like a school bus. Everyone has such good opinions about Lakeshore otherwise, and I agree that the atmosphere and approach to pre-school there is terrific, more in line with what I want for my daughter. Can anyone give me some feedback about these issues?

First, the LCC vans are not minivans; a special permit or license is required to drive them and they carry, I believe, 12 passengers. The vans have seatbelts, and the children must use them. Parents who want their child to ride on the school van in his or her own carseat only have to leave the carseat at the school the morning of the trip and let the teacher know it's there. Few parents do, for whatever reason. On the field trips, there are enough adults in the van to keep an eye on the children, to insist that they stay belted and safe. Also, sometimes a parent will drive from the school to the trip destination in her/his own car, and of course a child whose parent left a carseat can ride along.

Second, unless I'm mistaken, most of the big yellow school buses ridden by millions of children each day are not even equipped with seat belts. And surely there are children on those buses, who are driven to and from the school bus stop in personal cars, in a carseat they are still legally required to use because they are under 40 pounds. This is apparently legal. Lorraine