When someone occasionally engages, I extremely quickly dismiss them in the most polite, but firm, way possible. I also intentionally keep a demeanor that generally signals I’m not open to random conversations (I avoid eye contact etc.), but that often doesn’t work. At the gym it is particularly problematic, I’m focusing on gathering strength for my next set and sometimes people bother you even if I am wearing headphones.
I truly do not have a problem with who I am, I’m comfortable in my shoes.
As such, never in a million years I would approach a stranger to strike up a conversation, it would seem an incredibly rude thing to do towards them, on top of clearly not having any desire to engage from my side.
I’ll talk for hours straight to my wife, close family and the very few friends I have though!
And I think that's the answer; people who don't want to talk will simply tell you! And everyone carries on.
Obviously you should not bother people, but even in random encounters many people absolutely loves to talk. In many you can see their eyes light up if you talk to them of ask them a question. The internet has us so conditioned to believing that people just want to be left alone that we miss out on a ton of wonderful human interaction.
We honestly can't keep both talking about a loneliness epidemic and at the same time push the narrative "don't talk to me ever". We should absolutely respect e.g. people on the autism spectre or anxiety and their issues with talking to strangers, but I feel like we're allowing them to dictate a mode of interaction, or avoidance thereof, which isn't healthy for the rest of us.
It's one thing to not want it and to be comfortable not wanting it, but viewing it as rude goes way beyond that and is not rational.
I am bothered by random people wanting to talk to me -> Randomly talking to other people would bother them -> Bothering people is rude -> Randomly talking to people is rude.
Hence why the platinum rule is better. Once you know that other people (apparently!) aren't bothered by randomly striking up a conversation, you can adjust your actions accordingly.
No, that rule does not say "it is rude for others to do unto you differently from how you would do unto them"--it's about how you should behave toward others, not a justification for your negative judgment of how others behave toward you.
I agree that the platinum rule is better, but that difference is not the problem here.