pasteurization

One of the more concerning recent developments (since around the beginning of this year) is the confirmed transmission of avian flu to dairy cows.
Every single day, you take several IQ tests. You just aren't aware of them.
Why is it that some of the best public health measures, with proven effectiveness, are shunned by some people?  Of course, vaccines are the canonical example of this. Now, we can add pasteurization. 
In spite of the fact that fewer states allowed the sale of raw (unpasteurized) milk in 2010-2012 than in the previous 2 years