Outrage over athletes' behavior towards fans who approach them in public only exists in those who feel they are entitled something from the athlete. There are hundreds of thousands of people who think they are entitled to some form of casual courtesy from each player should they chance upon a casual interaction. For each of us, the 5 seconds we see a Marshawn Lynch or a Doug Baldwin is incredible - but for a Marshawn Lynch or a Doug Baldwin, random strangers likely approach them multiple times a day when they're out in public.
The OP took Baldwin's reaction super personally. For all he knows, he was the 15th dude to shout at him that day, and he wanted a little peace and quiet on a walk with his girlfriend. I'm sure it's a little annoying to be called out repeatedly in a crowd, and probably makes a guy feel exposed when he might be trying to play it cool.
Fans and media love to judge celebrities and athletes for anything they possibly can. They also love to believe they're entitled to something from them. If a guy is a loner, never wants to talk or sign jerseys when he's not at work, and doesn't want to give interviews, he's rejecting his responsibility to the fans. If a guy is extremely outgoing and goes out of his way to make every public appearance he can, he's a glory hound. We love to make judgments about their very character based on tiny little snippets of information we see with absolutely no context, and we expect them to give a rip about how we react to them.
But what's missing from the OP's rant is any ounce of acknowledgment for the fact that sometimes human beings just don't like to be yelled at by strangers. "It comes with the territory" and "he gets paid $X" become excuses to pretend that our favorite players are not people who can have bad days or get annoyed, but rather entertainers who job every day of their lives is to be their most affable self.
For our sake.
Because they owe us at least that much.