As a veteran of checking sketchy looking cardboard boxes full of things, this is basically the opposite of my experience. The TSA nearly always seems to decide to open my cardboard boxes and poke around inside, but the good news is that they have convenient "inspected by TSA" tape they will use to reclose the box and disclose that it has been inspected.

Don't expect the reassembly of your carefully packed box interior to be professional, though - although I imagine you wouldn't have a problem with factory foam inserts for a tablet pc.

I'm actually of a different mind than the others - you would be at very low risk of theft here. For jewelry and small electronics - even laptops - it would be possible to smuggle out the prize from the airport in a backpack or under a shirt. It takes serious cojones to do the same thing with a 20+ inch monitor! Don't expect the airline to take liability for damage, but I don't see this as any riskier than sending it via uninsured fedex or UPS.