Agreed. I believe it's well within Google's ability to auto-edit the sponsored segments out within an acceptable error margin.
No. That's what should be the case, but there are entire channels which don't do that or only half-ass it, and I've seen reviewers who just quickly say "thanks to <company> for their support" in the last 10 seconds of the video because they know no one pays attention anymore at that point. Quite a few review channels also do not correctly communicate that the links in the description are affiliate links etc.