In a long post mostly about a different issue, Zvi Mowshowitz writes:

I also strongly endorse that the default level of reliability needs to be much, much higher than the standard default level of reliability, especially in The Bay. Things there are really bad.
When I make a plan with a friend in The Bay, I never assume the plan will actually happen. There is actual no one there I feel I can count on to be on time and not flake. I would come to visit more often if plans could actually be made. Instead, suggestions can be made, and half the time things go more or less the way you planned them. This is a terrible, very bad, no good equilibrium. Are there people I want to see badly enough to put up with a 50% reliability rate? Yes, but there are not many, and I get much less than half the utility out of those friendships than I would otherwise get.

First of all, I'd like to say that nothing in my post should be construed as saying Zvi's desire for reliable friends is invalid or wrong. It's disappointing to expect a friend to come over and then they don't. If you're a busy person, on vacation or otherwise limited in time, a friend's canceled plans may mean that you've missed out on an important opportunity to do something productive and/or fun. It is very reasonable to want to befriend people who will reliably show up places they said they will on time. However, I do want to explain why I myself am quite unreliable and how I benefit from a social norm in which this unreliability is acceptable. (We should also note that I have lived in the Bay for the majority of my adult, actually-socializing life, so I may be unfamiliar with the benefits of a non-flake lifestyle.)

I primarily get places through public transit and Uberpool. The Bay Area's public transit system is really really good compared to public transit in most of the rest of the country (for one thing, it is possible to get places on it). However, our public transit is certainly inferior to, say, New York City's. One of the ways this works is that sometimes, based on the Inscrutable Whim of the Train Gods, the train will choose to show up fourteen minutes late. Uberpool also has high variance in time estimates, because they have to pick up and drop off other people. What this means is that when I say "I will get there at such-and-such a time", I mean "there is a bimodal distribution of times when I could show up which is centered around this time and probably has a standard deviation of like five to ten minutes."

So there are ways I can fairly consistently show up on time. One is that I could take UberX wherever I'm going and eat the extra expense-- although doing that consistently would trade off against my goal of using money responsibly. Another is that I can plan to show up on average ten or fifteen minutes before I'm supposed to show up, and then most of the time I will be on time. (This is what I do for doctors' and therapists' appointments.)

There are two problems with adopting the latter strategy in general. First, my time also has value! If it's bad for me to show up ten minutes late because the person is waiting around being bored, then it is also bad for me to show up ten minutes early so I have to wait around and be bored. Second, in many cases, showing up early is just as inconvenient for others as showing up late. For instance, if a friend invited me over for dinner and I show up fifteen minutes early, they might be still in their bathrobe and really counting on that fifteen minutes to shove the floordrobe into the closet and take the garbage out. That would be considerably ruder than showing up fifteen minutes late (at least if you keep them posted), because at that point the food is probably only beginning to get cold.

(I guess I could arrive early and then hang out on a street corner until it was time for dinner but see above re: my time has value.)

In general, instead of trying to always show up before you said you would, I think the best strategy is to try to be early about as often as you are late, unless it is something where being early is much much better than being late (a theatrical production, a doctor's appointment, a job interview) or vice versa (a party with lots of other invitees).

However, Zvi didn't just talk about being on time: he also talked about flaking. My local corner of the Bay seems to have less of a flaking problem than his corner. I, a diagnosed agoraphobe, still manage to make the majority of the social events I agree to go to, and many people of my acquaintance make as much as ninety or ninety-five percent. (Maybe I am particularly charming and people don't want to flake on me, or maybe I'm proactive and flake on them first.) But I think it is very useful that no one gets angry at me for flaking as much as I do.

I'm scared of leaving my house. This means that when I make social arrangements a lot of the time I won't end up actually going to them because I will be too scared of leaving my house. Whether I'm going to have a good mental health day or a bad mental health day is hard to predict even a week in advance, because it depends on short-term triggers like whether I've fought with a close friend, whether the assholes across the street have decided to set off fireworks, whether a person has said something unpleasant about me on the Internet, whether I've been doing a good job of remembering that in spite of what my brain tells me doing things will make me feel better and not doing things will make me feel worse, and so on. So the only way I can achieve any sort of reliability in social arrangements is by not making them.

I do not want to not make social arrangements. Social isolation makes my mental health worse. And doing literally anything tends to make me less depressed. I am also informed that some people would occasionally like to talk to me [citation needed]. So therefore I have decided to make plans anyway, and push onto my friends the negative consequences of dealing with my flakiness.

It seems perfectly reasonable to me that one would object to this state of affairs and choose not to have me as a friend. (This is one of many good reasons why someone might not want to have me as a friend.) But I think before advocating for a complete shift in social norms one should consider the benefits the social norms already have to those participating in them.