urbanriot Welcome to the world of being a parent, you time is theirs.
Sounds like you volunteered (perhaps someone did on behalf of you) for the job in a trip which was not part of a one of the schools team sports. Parents do chaperone kids around on those sort of extracurricular trips and are necessary, very necessary. Few parents have the time or inclination to do it, some perhaps don’t have the skills to manage more than their own kids. Clearly you know the sports and probably had some enjoyment yourself and didn’t have to worry about what the other kids were up to while on the slopes. You did sign some sort of document but Liability wise, as you describe it, you would be on the hook for everything if shit happened. The kid’s fight and one jumps out - your fault, kid opens a window and throws something at another car - your fault, parked and get rear -ended by a mac truck - your fault plus they would to after the other vehicle too, and on it goes. If the worst thing happened the parents of the kid would go after you. Hell if you wife was in the car and hurd badly there are valid legal reasons why she should sue you too. The whole insurance thing is gross mess but there is a twisted undeniable logic to it. Since 2001, and more so now I wouldn’t even want to try taking a car load of kids which weren’t mine into the US let alone travel alone at present day.
To the question, teachers should not be driving kids around in their personal vehicles, again in most school boards a teacher can’t even talk to a kid alone in a classroom, the door has to be open or another teacher or if they can find/grab the VP has to be present and this is because of allegations and crimes of the past. I get it, Ontario is a vast area and even though we are mostly in a small portion of it the distances are still large. If teachers didn’t do this it would be mostly the end of school team sports, few parents would have the time and really who the hell would want to deal with the responsibility let alone liability if something bad happened. I do feel that it being part of school activities that transportation should be covered by the schoolboard’s. At the very least they should come up with some sort of umbrella insurance that covers and protects the kids if something happens (and the teachers union likely would demand similar coverage for their people too). Looking at the information I can glean from my own area schoolboard’s policies teachers need only have minimum insurance and a valid licence, that seems insanely low. Unfortunately this board has, through entirely its own mismanagement come under the control of the Province and as such most of the public documents related to school clubs and or trips are locked out pending review so I can’t access the current requirement.
Recall a few years ago a school in Toronto took kids up to Algonquin park and one drowned, it took years for that one to get through the courts and the errors made were breathtaking, the kid should have never been on that trip: https://www.cbc.ca/news/canada/toronto/nicholas-mills-jeremiah-perry-drowning-tdsb-verdict-1.6201341