I agree there wouldn't have been (much of) an advantage to that sort of behavior if Google had started with paid services from the beginning and never depended on advertising.
However, now that we're where we are, it's just so easy to keep tracking you, since they'd actually have to go out of their way to remove it from their tech stack, that doing it on the off chance that either A: someday you'll stop being a paid customer or B: someday a PM will need to show more revenue and they decide to stick ads on their paid service anyhow, the combined probability of which approaches 100%, is worth doing it. Path dependencies can cause strange things to happen.
I can't trust a company who has tracking everything and everybody woven into their tech stack at every level to stop.
However, now that we're where we are, it's just so easy to keep tracking you, since they'd actually have to go out of their way to remove it from their tech stack, that doing it on the off chance that either A: someday you'll stop being a paid customer or B: someday a PM will need to show more revenue and they decide to stick ads on their paid service anyhow, the combined probability of which approaches 100%, is worth doing it. Path dependencies can cause strange things to happen.
I can't trust a company who has tracking everything and everybody woven into their tech stack at every level to stop.