What you're saying is true, and when riding in those conditions I choose to wear a high-vis and helmet.
Nonetheless it is victim-blaming to make it mandatory (nevermind doing that in broad daylight). There's always more that could be done ; clown hat, flashing lights, police escort, machine guns, F-35s. We have to draw the line somewhere, and if headlights are good enough for cars, they're good enough for cyclists. Cars would also see fewer accidents if they were covered in high-vis paint, yet curiously no-one is arguing for mandating it.
Americans loooooooooooooooove pointing out at their population density as a thought-terminating cliché although it's very rarely relevant to any discussion.
The size of your continent does not influence the size of your metro areas, dipshits. LA isn't the way it is because Wyoming is empty, LA is the way it is because a bunch of dumbasses decided that local mass transit and terraced housing should be outlawed and bulldozed in order to fuck over African-Americans communities.