Good thinking.

Yeah, kids are ready for self-carrying (and later, self-administering) at different ages. It's very individual.

The field trip thing is hard. We basically look at ANY disruption to standard routine as being high risk. So, with that in mind, holiday parties, field trips, testing days, substitute teachers, etc. are all higher-than-usual risk for human error. You'll want to build extra safeguards around those things-- probably spelling out responsibility for meds, for checking on safety, etc. much more explicitly than in the usual school day.

This is why in-class surprise treats are so problematic. Many parents choose to have a "treat box" for their child in the room, but there are a few things to think about with that choice. Who will have access to it? I've heard more than one story about safe treats being replaced with not-safe look-alikes by a well-meaning staffer that raided the stash. Also, at 6-8yo, a lot of kids begin to REALLY dislike being different, and for them, the safe treat box becomes an emblem of exclusion... and you can bet that the adults in the situation think nothing of leaving your child out several times a week (without even telling you) if your child has a safe treat box.

Thirdly, there are teachers who simply FORGET to let the child get anything from the box. Subs may not know it exists-- and may give your child unsafe items along with his/her classmates.

I'll second the notion of REALLY not trusting school staffers to decide on food safety. They don't have the day-to-day experience to draw from, so they are far more likely to make mistakes. What works well for some parents is to use a STICKER to indicate to the child that a particular food item has been checked and approved by mom/dad. Another word of caution there, though-- be wary of cross-contact in handling/serving of group snacks. It does no good to have 'safe' tortilla chips sitting next to the eggy veggie dip and a crowd of people reaching into the bag. KWIM?

Schrödinger's cat walks into a bar. And doesn't.