Specifically, I would assume the calculus is about "how much damage does this do by existing" versus "how much risk is there that we attempt to shut it down and sue and set a precedent by losing", and because for most projects the first value is tiny and the second value is potentially enormous, companies leave them alone.

When either value changes drastically in scale (e.g. a project does something making it very cut and dry which side of legal precedent it falls on, or to massively increase the damage to The Brand(tm)), that's when you get worried.