Google and ad blockers
Thinking about Google responding to the popularity of ad blockers by trying to put up technical barriers. I'd say they're putting enough effort into it that they must consider ad blocking a threat to their business.
Yet I don't see them making any attempt to address the critical problems that make ad blocking necessary. I figure they feel they either can't fix those problems, or wouldn't make money if they did. Either one would mean their business can't exist without scams.