I would think if your son wanted the school lunch he should have it. You don't know the kids at school and whether they ridicule him or not, but honestly these days I'd let him decide. First of all he will eat what he wants. Second of all tell him it's ok for him to tell you why he prefers school lunch to bringing his own. Ask him if there is a problem and watch what and how he tells you.Who knows? maybe he is threatened at school to give his lunch. money to someone it's happened to plenty of kids. These days are tough for kids in school because kids ate tougher than they were years ago. they don't often want to share it with parents and maybe with good reason, in their heads anyway.
Some kids PREFER to take their lunch because of the taste of school food. Most of my kids never minded the school food so yes... they got money every day for lunch. One of them refused to eat that stuff and packed his own.
Out local school system works on an automated debt card system as part of the student ID. That way the children are not carrying around a lot of money and the cashier knows that money is being used by the right child. Parents can then add more money on-line if the need arises.
It also eliminates the stigma associated with the free and low-cost lunch programs since everyone is using the same system.