They really should charge imo if it's not parent's who can't afford it.
In my school we as staff are paying for own masks - the school can't afford to supply them and the government aren't funding it as you know. Budgets have been hammered by covid already.
When masks in corridors were introduced everyone had to produce and put on a mask (unless exempt) in order to enter school. Parents were warned in advance that if kids arrived without masks they would need to be collected or brought a mask before being admitted and they had a little holding pen near the bus bay. Ds forgot his mask one day (non teaching day for me) and I got a phonecall letting me know he was in the pen.
I was quite surprised as we don't seem to do anything even about the kids from relatively affluent homes who turn up endlessly without essential equipment like pens but fair play.
We would always help struggling parents beyond the levels of what you'd expect I don't think we should be giving masks to kids whose parents just can't be bothered to supply them rather than can't afford it. We can't afford to provide ppe to staff let alone kids whose parents can totally afford it for their children.