Google could also have allowed invisible pay-for-placement without marking it as an ad. Presumably they didn't do that because undermining the perceived trustworthiness of their search results would have been a net loss. I wonder if chat will go in that same direction or not.
Pretty sure it's illegal to present advertisement and not label it as such in some form.
But as with everything, as new technologies emerge, you can devise legal loopholes that don't totally apply to you and probably need regulation before it's decided that "yeah, actually, that does apply to me".
