I understand what you are saying..........
I don't know how long you have been a fan of TWD but way back in the beginning it was explained by the writers that "Zombies" were never a part of the vernacular and thus the survivors never knew how to deal with them other than from experience.........
So the same philosophy applies here, lots of dying creepy people and the authorities trying to keep this mysterious disease under control...........
And to be realistic, without realizing the consequences of this virus that is spreading like wild fire, you just don't go around shooting people in the head who look "sick"...even tho you and I in the viewing audience know they are going to be zombies.
That makes this a fast spreading contagion. Then, recall from TWD at the CDC lab that everyone had the virus, but it did not activate until their deaths.
And media and social media went down not long after the pilot so I don’t have a problem with that aspect.