Google and the reCAPTCHA network aren't even that good with fraud prevention. You would think being literally omniscient over the whole internet would make it trivial to catch account takeovers, and Gmail has a proven track record at resisting account takeover, but when we tried to integrate their fraud signals, they were worthless, worse than the rest of the industry, worse than our homegrown trash from a decade ago.

Because Google doesn't actually care about preventing fraud, they just want the data you feed them and the fraud feedback you provide. It's all take, no mutual business.