>The whole smile.amazon thing was mostly to avoid paying advertisers and search engines.

Exactly. Someone explained it well on here in another thread. But the quick proof is how it worked. You didn't set a option in your amazon account saying "donate to red cross" or whatever, and then just forget about it and go about your business as usual, which is what would make sense.

You had to intentionally type "smile.amazon.com" into your browser to start the shopping session. This ensured that you weren't starting shopping by clicking on an ad link or google search link or whatever.