I have a friend who seems to see the next stage of carseat as something achieve, as a sign of growing up. She moved her two DSes (3yo - the same as my DS1 - and 1.5yo) into stage one carseats when they were each around six months old, because they 'looked cute' and 'it made them look like big boys'. She has never had the straps tight enough for either of them - my DS1 used to be quite a chunky monkey, compared to her skinny DS1 definitely so, and the straps were pretty lose on him once when she gave us a lift into town. I tightened them quite a lot.
She's just posted a picture of her DS1 on the dreaded Facebook in a stage two carseat (the one meant for 4-11 year olds, I think) and said that she 'just thought she'd try him in it' and that he 'really likes being a big boy in it'. Well, that's lovely maybe, but what if she has a crash? Is it actually dangerous for them to be moved up before they're big enough for the next stage of carseat? I'm assuming they have stages for a reason.. there is no way her DS1 is anywhere near the 40lb weight limit or that he's tall enough to warrant a new carseat, he's very slim and petite.
Should I say something to her? AIBU to get involved? I genuinely don't think she even thinks it's all that dangerous, or that there are any risks involved in not having children properly secured in the right stage carseat..