I agree that they made some moves towards reality, but oberall its a soap opera. The Brits do that type of grim apocalypsia tale so much better - check out The War game” or “Threads” for video examples. Even when they’re unrealistic, it is pl;ot silliness. The gritty details are fine.
As to literature, the Brits produced Death of Grass, the Triffids, The World in Winter, etc (they’’re just my favourites, though dated). Jericho’s makers could have read Alas Babylon and taken many good pointers on...also Resyrrection Day.
Ah well, it’s all fun, it just irritates me because if it had had a brutal real edge it would b an enduring classic not just a brief wonder.
Androcles, you mentioned the Brits, but also there is a popular Australian book series about Australia being occupied by a foreign army (ethnicity/country of origin is never stated). It's for "young adults", but it's still one of my favorite book series - Tomorrow, When the War Began. Although it's not very realistic, I suppose; but it's like Red Dawn in which the scenario is very interesting.
I tried watching Jericho, but the characters drove me NUTS. They seemed ridiculously brainless. My mom and I couldn't stop laughing after a scene which I'm assuming was supposed to be dramatic. It was pretty melodramatic instead!