The first day my kids started school in New Zealand I couldn't believe the open gates, surely anyone could come and go as they pleased?! No padlocks or key pads on any of the gates, the reception with a wide open door and you can stay at school after hours and play on the amazing playgrounds (and on a weekend too)!
In complete contrast, our London school locked down the minute the kids were inside. Similarly at the end of the day we all duly lined up and waited for the gates to be unlocked to pick up our kids. Access to the school during the day was via reception where you had to be buzzed in after being scrutinized on the TV monitor.
With a history in London of being restrained by teachers and trying to escape, not once has my daughter walked out of those open school gates (as I feared). Reverse psychology clearly works!