I think the new phenomenon is how many people are now on the asshole's side, or are in the neutral "don't get involved" camp.

No, I don't think that assholes are a new phenomenon, and I agree that rude and entitled behavior has always existed. However, societal norms and expectations regarding how to handle such situations may have evolved over time. In the past, confrontation might have been more common.

I would have no problem calling someone out for being a shitty person in that scenario. How people respond has probably evolved a bit with social media and cell phones but it’s not my problem if someone reacts immaturely to me pointing out that they’re rude.