If my kids were ever in a daycare situation I would never tolerate anyone speaking of my children that way.
"I have to be sure that MY kids are going to get home safe". Even if car seats had magical powers that would be sure to get kids in them home safe the kids are not your children. Let me repeat. They are NOT your children. Making a statement where you refer to someone else's children as "my kids" would be an indication to me that as a child care provider you are overstepping your bounds and have crossed into the realm of creepy. Ever see the movie "The hand that rocks the cradle"? I would not bring my children back and would also tell the other parents about it. Even if my kid's grandparents said something like that my kids would no longer be allowed alone with them.
Parents talk. If the OP is serious about her daycare business and needs the income saying things like this or calling the police could ruin all that. She would be blackballed. As a parent I know I would not take my kids to a child care provider if I had heard about that provider calling the police on parents. I think mentioning it to parents, giving out pamphlets or papers, having a safety day, offering to buy carseats for the kids, or telling a white lie about it being a new requirement for you to check or something like that is what should be done.