In my experience at the Commodore, it's usually 19+ because they serve alcohol (but maybe it's different for Mika?). It's really a shame b/c there a lot of young Mika fans who want to see him in concert.
Edit: I checked the Toronto venue and it is an all ages show while some of their other concerts are 19+. So I'm thinking it might be all ages at the Commodore. So maybe the ticket price is higher since the venue can't serve alcohol?