If you signed up, then you opted in. Don't be lazy and mark things you signed up for as spam. I'm not understanding how people get email from Amazon that aren't customers, and how customers can't turn off everything but confirmations, which I know is possible, because I have.
I'm a customer, I consider that opt out. You don't? I signed up for amazon, not their bullshit emails. That you consider the situation opt in shows they have you trained well.
That said, this is no excuse for Google to mark their transactional emails as spam for people that clearly want to receive them. Google is just being lazy and doing a bad job. Even Yahoo gets that right, Google can do it too.
of the 64 emails I have from them 50 are spam of this nature.
just because i signed up for amazon.com, doesn't mean they get to spam me crap because they've buried a 2pt font unsubscribe feature that may or may not work over the course of a few weeks.