Google introduces a way to reject all cookies... But only in Europe


After being hit with a fairly hefty €150 million fine by regulators earlier in the year, Google has added a new Reject All button to the cookie consent banners that have become ubiquitous on websites in Europe.
Google says that the change is in response to the fact that, "regulators who interpret European laws requiring these banners [...] have updated their guidance for compliance". So what exactly does the change mean, and is it likely to extend outside of Europe?