It started with boats, but over the centuries, it is practiced everywhere... we establish cultural rights of way, a hierarchy of precedence about who gets to go first. We need a default because we can't always have a discussion about who goes next in the moment.
Motorboats, for example, are generally expected to veer out of the way of a sailboat (instead of the other way around). This makes sense, of course, because they have more options and can recover more easily.
That's one way to prioritize who gets to go first: the small over the big, the one who needs it over the one would could handle the interruption. It's annoying for the motorboat, but vital for the sailboat.
Lately, we seem to be making some new decisions about right of way that change this perspective. That cars ought to have right of way over pedestrians and bicycles. That huge corporations have right of way over individuals. That the authorities have the right of way over the presumed innocent, and that the marketer's infinite need-for-attention has right of way over quiet and privacy.
What would happen if the default was that roads are for pedestrians and bicycles unless otherwise stated, and what would happen if pleasing corporations was seen as an exception in the priorities of those that regulate them?
[There's no right answer in issues of societal right of way, there is nothing but compromises and judgment calls. At either extreme, everything breaks down, and so the question is: where do you want us to be? Where do you draw the line? Is it up to us?]
It's possible to argue that roads are more efficient when bikes don't clog them up, and that our illusion of security increases when the default is to know everything about everyone. Most of all, that corporations are more profitable when they don't have to worry about the people who don't fit their model.
It doesn't seem like much of a cost to ask individuals to get out of the way, until, all at once, we realize just how expensive it was to totally prioritize power and efficiency over humanity and justice.