... We mainly enforce the 18+ rule for the fact that underage players are not liable for themselves. If an underage player gets badly injured on the feild. The owner himself is often held liable for the kid. Some feilds allow kids to play if a guardian is present, but a lot of them save themselves the hassle and simply dont allow it all together.
Along with that, Rather than weeding out kids with the age verification system. The system helps prevent realistic looking weapons from getting in the wrong hands, as they could be used for crime to an extent. Though, It seems that purpose is starting to get nulled out with the cansoft lines being sold publicly around the country.
So don't think we're giving you shit for being a kid. Its a general rule all together.