The way COVID is spread is through someone who has it (or is carrying it) to exhale it and someone inhales it. If you take that into account, that's why social distancing, masks, and lockdowns were pushed.
Biohazard bins are for proper disposal of things like needles, and other things that you can contract things through physical contact. Since COVID is contracted through airborne means and not physical means, you don't have to dispose of the masks in biohazard bins. You won't catch COVID from touching a mask like you would Hepatitis from a used needle.
The whole "protecting others" bit is because people weren't doing it. If you were walking around without a mask (or dumber, wear a chin diaper), and you were unknowingly carrying COVID, you could have exhaled it to someone healthy, and they would have gotten sick because of you.
The McDonalds rant is really pointless, as you getting high cholesterol from eating a Big Mac doesn't affect anyone else but you. Cigarettes are debatable due to second hand smoke, but if you're far away from people, you're not hurting anyone but yourself.