True, but the people in charge of protecting NZ from foreign food are responsible for protecting NZ from foreign food. That job includes stopping people from smuggling food, a job best done by preventing passengers from trying (accidentally or intentionally). If NZ has to issue fines to this many people from one flight they're not doing their jobs very well.

For example, if an airline passes out bags with illegal stuff in them, it might not be a bad idea to require them to tell passengers that it contains illegal stuff. In case they haven't realized it, people are idiots.