What would it cost you to be nice? Massive amounts of energy. People rarely understand that, or believe it even when explained.
Why not be nice? Because not only is it an effort, it doesn't work as advertised. The positive reactions predicted rarely, in fact, manifest and negative results are more common.
Why doesn't it work? Because it's not what people want. It's not the same. It's a facsimile. Holmes is honest about this, but people don't care; they want him to go through the motions of meeting people's expectations, when it is neither natural for him nor effective, and they blame him for it. What's natural to him is unacceptable to most other people, and usually the best he gets is being treated like a useful nuisance, tolerated only for sake of what he can do. He's different in ways that he can't cover up and other people notice, regardless of how much effort he puts in. They're not satisfied with going through the motions; they want him to be something he's not.
So I got to thinking, this is really a lot like the uncanny valley problem in AI. When faced with an obvious machine or animal, people are okay with it. When faced with something that is almost, but not quite, human they become uncomfortable, and often violent on verbal or physical levels. When it's just a robot they're flipping out on, it can be kind of funny.
When it's a person, it's not funny anymore. And I'm thinking this effect may underlie some of the impatience, revulsion, and abuse that comes up with a variety of people who look like other humans but don't act that way, or have the same personality but a different appearance. It creates a glitch in the interaction protocols of most other people around them. So even if the person is exerting maximum effort to fit in, to be pleasing, the success rate is extremely low -- not because of them, but of other people. It happens across a wide range of traits. People with autism. People with disabilities. Otherkin. Anyone whose difference is enough of a barrier to interaction that the sheer weight of probable failure makes most or all interactions nerve-wracking wondering if it's going to end in another disaster. And sure, some people learn to fake the demanded presentation well enough to get by, but a lot can't no matter how hard they try.
So for fucksake before you yell at someone, check your wetware. Check it like you would debugging for any other cognitive distortions. If that "not a real person light" is on, you've got a problem. Then check your response. Because you may be flipping out on someone, demanding stuff they just don't have. And if someone is busting their hump trying to fake it, then have the grace to accept the effort as intended even if it's clumsily delivered.
It doesn't mean you have to put up with someone you can't stand or with anyone mistreating you. But make your objections clear, and base them on actions with practical consequences instead of just social expectations. Eye contact is a purely social expectation, which varies across cultures. Don't use physical or verbal violence is a safety rule. Etiquette is a big mess of mostly unwritten (or only written in obscure places) rules which may have aspects of both, and is often better handled with straightforward negotiations like "I will handle all of the vermin control if you will handle all of the bookkeeping." Ideally, relationships should be equal and based on respect. Any relationship in which one person is expected to cater to everyone else's whims without return or respect is unlikely to be healthy, and it doesn't matter which direction that's going in, it just tends to cause problems.
Pay attention to that uncanny valley. People can get lost and hurt in there.