Back to the OP's original post.....
Most big box stores outsource things like the insurance question brought up. We received that mailer also...and it was shredded as we are happy with our coverage.
Costco's main thrust is large quantity items and we take advantage of those things like toilet paper, paper towels, printer ink cartridges, dog food....you get the drift . We are traveling about 10 months of the year and we wish there were more Costco stores available.
With that we like other box stores as well...but you need to shop!!
To blindly say they will drop a store like a Costco because of an outsorce issue, like auto insurance, for their shopping is....well...not good shopping.
To each his/her own.