Exactly. Buying billboards on the most expensive streets in the world is very expensive. Having your customers sitting lined up in a row in coffee shops with their laptop lids with the lighted apple logo pointing outward to the street on these very same streets must be very valuable advertising. I'm constantly amazed when I walk by coffee shops and see the typical 75% apple market share, when just a decade ago they were really a niche player.
It's only when it's off that they would miss out - but most of the time if my laptop is out of my bag then it's on.
It still took them a while to put them on the right way up. The first few laptops they sold with the Apple logo on the lid, they were oriented so they were "right way up" for the user when the lid was closed. That made them all upside down in all those tech conference shots from the stage...
There is already something similar on one of the numerous android handsets out there where the 4 hardware keys turn 90 degrees when you switch from portrait to landscape mode. Not quite as polished, but similar in concept.
You can verify that by changing the display brightness, the logo will change brightness accordingly. Or just hold the turned-off laptop in front of a bright light source, the apple-shaped hole wil, be visible through the screen
Also, I'm not sure how the computer would look without a logo interupting it. I guess almost every other manufacturer comes close to this, but I think an Apple computer would feel wrong with a a view of unbroken alumninum.