At least from what I've seen in the Costco stores in Australia, it's because a Costco 'express lane' would need a cutoff of about 30 items to make it useful. Pe

At least from what I've seen in the Costco stores in Australia, it's because a Costco 'express lane' would need a cutoff of about 30 items to make it useful. People go to regular supermarkets if they need something quickly, and they go to Costco do to their weekly/monthly shopping.