They didn't do it because of oil (well to take for ourselves). They did it because Venezuela has been cozying up way too much to Russia and China, and sending both of them a lot of oil.
You're missing that those 80% are not the same people every year. The IRS definitely doesn't keep a database of who is married or not, nor are they scouring every counties database for changes. I'm not sure where you're getting the "they will just send you a letter" part.
I think a couple more have caught on, but Netflix was one of the first I think to let you press a button to finish your email login for popular email providers. So you could press the "@gmail.com" button instead of typing it all out. Doesn't really matter on a computer, but was nice when signing in on a TV.
I could be remembering it wrong, but I'm pretty sure Google's webscraper was far superior to basically any other search engines, and that along with it's ranking algorithm killed whatever need for webrings there were. I remember having to tell Yahoo about my website and they said their bot would look at it in a couple of days.