[Vansterdam]

^

Spoiler!

its probably because living on the farm they havent encountered any walking dead zombies recently that wandered on the farm/land.. im preety sure thats all gonna change with that bulletshot from andrea

i predict just like in the comic the zombies are gonna be hearing that shot from miles away and their all gonna just follow the sound until they reach the farm area.

herschel the farm owner also thought there would be some sort of cure in the future thats why he had all the zombies locked up in the barn cuz they were all close to him or someone he knew.