If you know what a midge is, think in terms of a mosquito larva, and bass and other fish can detect them. They're barely the size of some fishing lines. It's not the matter of the fish knowing the line is there, because they probably do, but how they react to it's presence.
Also, what does color have to do with anything really? Color is only what the anatomy of specific animals eyes allow them to see, with the light that is available. WE, use color as reference, because we see it. Not everyone see's it the same, as some are "color blind" nor does every other animal. Studies have shown that bass and other fish likely see colors similar to how we may see them, but doesn't mean they see them exactly in the same manner as we do.
However, you have to look beyond the color too. Even a clear line has a shape and substance, so it displaces water, even to a slight degree, and it likely is detected by the lateral line of these fish we chase. Color does not do that.
There was a lot of use of red for lines and hook finishes, and it was said that they "disappear" and become "invisible" which is a lot of hooey! The color is no longer visible at certain water depths, because there's not enough light, but the line & hook is still there. They are a mass that has substance, and you can bet if a fish can detect a midge in the water moving, they can detect that line in the water. But again, the important part is how they react, and I've never seen any fish spooked by a line, except a fly line, as it slapped down on the waters surface in shallow water, and that was the sudden noise that scared them, not the line. I've seen bass follow the end of a fly line, curious no doubt about the thin thing moving across the surface and fly lines are generally much larger than most lines used for bass fishing on other tackle.
I know that I've caught enough fish, not just bass, using hi vis lines of various types, that I'll never be convinced that it makes any difference if these fish can or cannot see the line. I'm sure they see a lot of things in their environment, that has little or no affect on their reaction to them. Unless there's a reason for them to react negatively, why would they? Lines are not a problem, and especially not the color.