People either dont believe in parasites, or just dont care/want to know.
I remember when I was with my ex, our cats all had worms and we dewormed them. I was very concerned about us, as we were living in small, dirty room with our pets (we were very poor). He told me that "humans cannot get pet parasites. they would just die in our systems" I remembered at the time wondering what he was basing that on and how he could know such a thing for sure. It seemed like he was just maKing it up to make himself and myself feel better. Hmph.