It depends on how you manage it. We had a system where parents could pay up front for your lunches, and students using that system got their lunches the same way the needs-based students did - the lunch lady just checked their name off the list for the day. You could guess at who had which, probably, but there was no way to confirm it.

That being said, you’re right about the bureaucracy and I’m all in favor of free lunches for all students regardless of their parents’ income.