[warent]

Great point I hadn't considered that before!

I'd guess it's for two primary reasons. 1: it takes workers to load and unload checked bags. Contrast to overhead where you are doing the work. 2: checked bags are pretty much unlimited. You can have several huge ones.

For some reason I was also under the impression that a checked bag was actually opened up and rummaged thru as well, hence the word "checked", but maybe I've just been misunderstanding?

[toast0]

I think it's checked in, as in you gave it to some one. Not checked in as in someone checked in it. That's not to say they don't get rumaged through, but they were checked bags before they got routinely rumaged.

[devilbunny]

TSA certainly may search your bag, but they're "checked" bags in the sense that coats are "checked" into a coatroom - they are handed over to someone else to be delivered to you later.

[celticninja]

Checked means checked in, or handed over. Not checked as in inspected. Whilst some bags may be inspected they are a small number of the total.