I'm an Aussie and I have always worn a helmet, started in U11's and I am now 19.
My dad had his 3 front teeth knocked out by a cricket ball while batting (he now has 3 fake teeth), he's pretty hopeless tbh, but my mum said either I wear a helmet or I don't play, so I have worn one from the start. When I first started they weren't compulsory, but then in under 13 they were, so everyone had to wear one up untill U16's. I rarely take it off because I don't like to change anything while I'm batting, so I try and keep it on, unless there are spinners from both ends. Top edging the ball into my face is also a concern, lol.