Right, this is why I compared it to car manufacturers. At a base level, there is little to no reason to prefer one car to another. Bicycles can be the same. That said, at the ends, there are people that latch on heavily to decisions and small differences in the options.
Now, again to your point, we are all on the same roads. Such that standardizing parts is incredibly valuable.
I /think/ the trap is that standards often act as constraints on the manufacturers. And software is a large industry where constraints are easy to effectively ignore during development. Memory requirements. Safety from malicious actors on the system. Capabilities of different computers. I could probably go on.
I suspect it is worse than that sounds, even, as developers tend to focus on the intrinsic quality of code thinking that is paramount. I hate that sentence, as it makes it sound like I don't think the quality of the code matters. I fully think it does. I also fully think we fall for aesthetic quality of code far more than we do any other quality.