Interesting.
I was going to watch Deadpool with my friends too, only here it's rated R aka PG18. All of us save for myself and another person had already turned 18 and were turning 19 this year. Both myself and my other friend had not turned 18. We booked the tickets online and they didn't even check. The assumption here is if you can buy the tickets then you're old enough to watch the movie not always the case though.