Dad mad about membership cards?

I been to Royal Ontario Museum (ROM for short) at least three times with my program. While all three times I went with the program I had a ROM membership card for it paid for by Mom. The first time I went with the group-I was able to use my ROM card.

When I told my parents later Dad didn’t understand why I was allowed to use the membership card while with a group “field trip” but Dad (back when he had one which might have been in the early-mid 80s or later) couldn’t for a school trip back whenever he had one.

Personally I think it might have had something to do with I was a participant in the group vs. Dad was a leader.