Do you want to be the person going around policing mask wearing?
First, some laws probably don't have any positive impact.
Second, there's a difference between accurately summarizing trial results and extrapolating that to the impact of a new law. If there was a death penalty for not wearing masks, perhaps compliance would be better than in the trials and an effect would be shown. This doesn't mean that the trial analysis is wrong, you just can't draw a conclusion about the law from the trial data.
Third, laws have multiple purposes including Justice and Punishment. Some murderers might have zero chance of re-offending but we still want to punish them as a matter of Justice, not because it makes Society safer.
Maybe this is a ridiculous metaphor since public health is not what the justice system is trying to accomplish by imprisoning murderers.
But also, you'll be fine to go on red in the middle of night, where noone is around. Personal responsibility is unfortunately removed by centralised regulations and laws. Thats the problem.
[1] "personal responsibility" makes little sense as a moral catch-all when ignoring your own health can cause other people problems
How much of Netflix cause health problem for you? What about food? How much of junk food are you eating? Or maybe we should ban tabaco and alcohol. Or profesional sport. All of that is potential threat for your health. Being overprotective could damage your mental health... etc.
More regulations = less personal responsibilty.
I will make a comparison, tell me how you find it: "Dumping waste into the river shouldn't be illegal because you dump your waste in your toilet every day and it goes to the river."
Does it sound reasonable? Sure. But I haven't defined scope and I haven't defined effect and I haven't even defined what 'waste' is; I just made up two scenarios which could have similar outcomes and then called it day -- but if you actually care about what happens to the world you need to get a little more detailed than writing silly grandiose political statements and making non-sensical metaphors comparing indicting someone for murder with crafting public health policy.
I generally think laws should be codifications of societal norms. Which also implies that as societal norms change so should laws.
So even things such as murder which people do and we don't want should be codified as illegal. But even if nobody committed murder anymore it should still be illegal as its against societal norms.