Actually, I went into a T-Mobile store last week and found the Nexus 4 on display as soon as I came in. The actual product was sold out. The Galaxy Nexus advertisements was plastering Verizon for months. So yes people can find the nexus in stores.
They can, but the question is, will the average consumer actually buy one?
Most people who walk into a T-Mo store are going to want a subsidized phone. That's the expected model, and if you're going to sign up for a postpaid plan like most Americans do you might as well get the subsidy to go with it. The Gillette model is alive and well in the USA.
Walk into a T-Mo store right now. Chances are, you'll see a HUGE SIGN that the HTC One S, the Optimus 9, and a few other phones are free. The Galaxy S2 is $150, the S3 is $280, and the Note II is $370. Most of the above are 4G phones. Many have SD slots. Most importantly, they'll all be on display in every store.
If you haven't been made aware of the Nexus 4, you'll not know to call ahead to find a store that carries it, talk to sales reps at that store until you find someone who has heard of it. Then you'll shell out $200 for a subsidized phone without LTE, without an SD card, no headphones in the case, etc.
Those of us who value the N4 for what it does are valuing it for something that the majority of phone owners in the US are (a) unaware of, (b) if made aware of it probably wouldn't care, and (c) if made aware of it and cared would only see it as one factor among many decidin... OH, LOOK, LTE!
With apologies to Douglas Adams:
Arthur Dent: You hadn't exactly gone out of your way to call attention to the Nexus 4 had you? I mean like actually telling anyone or anything.
T-Mobile Rep: But the phones were on display...
Arthur Dent: On display? I eventually had to go down to the cellar to find them.
T-Mo Rep: That's the display department.
AD: With a torch.
T: Ah, well the lights had probably gone.
AD: So had the stairs.
T: But, look, you found the Nexus didn't you?
AD: 'Yes. Yes, I did. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying "Beware of The Leopard".