[snsr]

They actually do, at least for the past couple of years. My past two iPad purchases have been clearly marked "AT&T" right on the label.

[cloudwalking]

I bought my mom a Verizon iPad a couple of years ago. Unfortunately I was actually sold an AT&T iPad. There was no indication either way on the box.

[craigching]

Yep, same here. I have a first gen iPad, a first gen retina display iPad, and a couple of iPad Air now and only the first gen didn't have the carrier on the box, but that's because the first gen was ATT only.