It REALLY depends on the school. Also as to which choices the child themselves make AND how many choices they are allowed to make.
My son loves fresh fruit..BUT... he had to choose between fresh fruit or more traditional dessert (cookie, pudding, etc). The cookie won out each and every single time. Ditto the other "choices". While the school had some *great* choices (better than the 'between 2 evils' thing a lot of schools have), because he wasn't allowed to just eat what he wanted (aka both of this but none of that)... it didn't work out well.
I still let him buy once a week (unless I'd forgotten the night before then more), but it was mostly because he REALLY liked the standing in line part. (kids are funny that way, they get thrilled about things we got sick of years ago).
The school we were *considering* going to for 1st grade had *phenom* lunches. But they were $15 each. Ouch. $75 a week was just not in the budget, but had it been (and had we decided not to homeschool) I would have been REALLY happy with him eating their lunches every day.