DD is not yet 135cm and a good bit younger than 12. She has a sports fixture with school next week which I'm unable to offer transport for as I'm working. It's about 15 mins along rural roads. I always have my DCs in high-backed boosters in the back of the car and have been subject to raised eyebrows because of this, not least on a long distance trip with a friend's DM. In that case I had wanted to travel separately suspecting that it would be an issue but agreed to travel with them in the end. I turned up with the high-backed seat but it was made explicit that DD was expected to go without the seat (she didn't).
Parents have been asked to assist with transport for the fixture next week. I'm aware of a teacher having given an even younger pupil a lift without a car seat in the past and there is nothing in the current request regarding car seats (though they do expect a DBS certificate!)
WIBU to say that DD can go only if she uses a booster cushion as a minimum? I know a lot of parents locally don't use any booster at all from year 1 or 2 but I wouldn't choose to take that risk with my DCs. This isn't an unexpected journey either. I feel like I've answered my own question here but am already 'that mum' having asked uncomfortable questions about a fundraising discrepancy recently.