Wow that’s crazy, a 10 year old in a booster seat? I guess better to be safe but like a previous poster mentioned surely car seat manufacturers need to accommodate for this now?

Perhaps this link will have info on car seats available
https://roadsafety.transport.nsw.gov.au/stayingsafe/children/childcarseats/index.html
As for getting the kid into them .. trouble starts almost as soon as they are old enough to refuse to get in the car! Perhaps taking breaks once in the car to make it as pleasant as possible and stuff like that could help get them in the habit of using one and not minding..

I am in NSW and unfamiliar with the changes? I thought it went by age and or height of the child, Under 145cm needs a booster, has this changed?

My 11yr old is not tall enough yet for an adult seat belt and uses a booster seat.

When I was young we didn’t have car seats past being a baby!
I really think a 10 year old is too big for a car seat but with the laws to come out I’m sure car seat companies will be forced to create something age appropriate as then how will people be able to follow the law?!

I don’t think you’re alone in this challenge! Hopefully car seat manufacturers will give us more, and more suitable options.