They have access to more competitive products through the Net and might be buying in bulk.
Been there. Done that.
E.g., my favorite brand of shampoo, which costs $11 at Whole Paycheck but is only $4 online (plus shipping, ugh!). So, what to do? Obviously, buy several years' supply, hitting the free-shipping threshold and then some, and evading the sales tax for good measure!
Out of the shampoo market until the Cruz Administration!