wouldnt the average refund come out to basically a free year of membership? the easiest thing for them to do might be just check who was a member during the tariffs, and credit their membership fee for the 'tier' they were buying

people using costco as basically a small-business depot would be lifetime non-transferable free members, and typical family/consumer gets some extra years, which they'll turn around and spend in the store anyway

win/win? costco members are sticky, and refunding cash is hard