Feeling? Google literally states this is one of their goals:
Every time our CAPTCHAs are solved, that human effort helps digitize text, annotate images, and build machine learning datasets. This in turn helps preserve books, improve maps, and solve hard AI problems.
Google does in fact have a self-driving car. You may have heard of it: https://waymo.com/
But captcha is mainly about fingerprinting users versus using it to train self driving models. Google is primarily an advertising company, so being able to track users' browsing patterns is more useful to their core business model.