Hi Troy,
Its called "Movie Magic"
No logic behind it. Its just to scare the c--p out of the viewers. Once logic is applied its no longer scary. Similarly "Looney Tunes" would not be funny if common sense was applied.
'Movie Magic' reasoning has us to extrapolate that Zombies require human flesh for whatever reason, I don't know.
Certainly not to survive. Yet the procedure results in the victim becoming one of them. Which means more competition. Again illogical. But necessary to perpetuate the species.
However, being eaten alive is one of the most scariest deaths that we humans can imagine.
(According to certain psychologists). Hence the adrenalin rush the audience experiences.
The plot and reasoning has to be simple enough for viewers to 'veg out' and not have to concentrate too heavily.
So ends my two bob's worth for now. I am not a fan of the topic as it is too far fetched for me. But I do not knock your viewing choices. I like Looney Tunes so I can relate.
Cheers Marty