Earlier quoted context omitted.
I included the part on free-riding/non-immunized populations because as the number of free-riders increases the effectiveness of herd immunity decreases, which I believe directly addresses your point of why people do care how many people are not immunized. You may not agree, but that's the reason people care.
Logically speaking someone with AIDS is a "free-rider" from this logical perspective. How is this person different from a healthy person that chooses not to vaccinate? The logical argument seems to be that "intent" determines if you are a threat or someone to be protected? Again, by the same logical arguments people with AIDS can't go to a foreign country that doesn't vaccinate?
The anti-vaxxers come along and free-ride, and for 10+ years, they think the are brilliant -- their kids do not get these mythologized diseases! But one day, enough morons start thinking that, that you reach a tipping point, and only 75% are vaccinated. All of a sudden, an outbreak occurs, putting all the immuno-compromised at risk, as well as the other 20%+ children of anti-vaxxers. Many kids die or become very sick. Suddenly, the anti-vaxxers realize they were playing with fire, putting children at risk.
What don't you get about this?