It has taken a fair bit of self-analysis, helped by my recent understanding that I am ADHD on top of autism.
I follow rules extremely to the letter. As a young man I used to (literally) kick the side panels of cars that ran through red lights.
A few years back I took a shortcut, through the checkout, into a supermarket, to make it easier with a knee injury. As I walked through an employee told me off, saying it wasn’t allowed. I have since realised that some of my strongest memories are from deep embarrassment resulting from not doing something correctly and being told off for it.
Rules give me the structure I need to cope with society. If normal people cross the road when the green man is lit up, I can do the same and be normal. Rules (the non-social type) are easy to understand and follow, and are everywhere if you care to notice.
Viewed from a different angle, I deeply fear being spotted as being different, and that can arise from breaking rules. Or even being wrong about something, or saying the wrong word. For anything outside of rules, I tend to prepare beforehand, to avoid getting it wrong. Or avoid the scenario.
I don’t know if it is an ADHD thing, but I also break rules all the time, at heart I am a rebel. But these are rules that are more about generic conformity, like hair style, that can be a choice. For many years in my 20s I had dreadlocks, long before they had any sort of popularity. Anything “alternative” is an attraction. I’ve even been a cult leader of sorts. But I avoid being told off for breaking real, actual rules, like the plague.