Are your students allowed leave school at luchtime?

Bang on.

The whataboutery of students being unsupervised knocking around town is crazy. Kids of this age make their own way to and from school without supervision.

Once the school policy permits it then parents have no comeback.

Many schools physically do not have the infrastructure to provide space for a canteen with hot meals. Where I work we'd have space for less than 20% of students to sit in the canteen. Our policy is to allow students who live close by to leave the school at lunchtime to go home once their parents have signed a permission slip at the start of the year. Those students are then provided with a lunch pass.

As said elsewhere schools have the authority to come up with whatever suits their own situation.

No there isn't. And it's not an alarming thought for management. Senior kids are down the town, junior kids are on the school grounds where they can hang around with kids their own age. It doesn't mean they are being bullied when they are all in the building. Amazing as it sounds we do supervise our students when they are on the premises.

Honestly, you have some very strange ideas about how schools operate.