I'm not sure I see much incentive with macOS. They might make a few dollars from ads but less than the hundreds of dollars they make when someone buys a macbook because they don't like the ads in windows. I've noticed zero ads pushed to me by the os in ten years of mac use. Also googling just now has them as the US's most profitable company making $100bn last year so I doubt they are desperate to change their strategy by shoving ads in.