NPR's "Planet Money" show has an interview with a founder of the Price Club, which merged into Costco, Robert Price. He explains why at Costco, there are no signs telling customers what is in each aisle. From the transcript:
SMITH: So yeah, making you pay to shop is this one big thing that Costco does that's the opposite of how normal stores work. But once they've locked you into this system, they can do all of these weird, secret things that wouldn't fly in any other store, but in Costco can get you to buy more.
GOLDSTEIN: I need Ziploc bags. In a normal store you would look at the sign at the end of the aisle that says Ziploc bags.
GOLDSTEIN: There are no signs in Costco.
SMITH: There are no signs, but why wouldn't you put a sign? Like, it makes no sense, right?
GOLDSTEIN: I asked Robert Price.
PRICE: I was adamant that we would not have signs telling people where things were because that would make it likely that they would wander through all the aisles and find other things to buy.
GOLDSTEIN: That's a little bit devious. It doesn't feel like you're looking out for me when I hear that.
PRICE: No, I mean, I agree with you. I think it was - I think - I don't want to use the word devious, but it was manipulative.
President Obama loves Costco, whose board includes high-profile personalities like Warren Buffett's partner Charles Munger. If it were some other store, doubtless you'd see the politicians proposing to require signs in aisles to prevent the poor customers (who no one, after all, is forcing to shop there) from being manipulated.