How did the world here turn to crap in just 20 years?

In Escape, the human world portrayed in the movie is just like the Los Angeles area was in the early 1970s, but in this movie, Conquest, set just 20 years later, the world seems to have been turned on it's head, with riot police everywhere, constant tannoy notices about dispersing gatherings and curfews, and a general unpleasant "1984" feeling, especially directed towards the apes.

Escape indicated that it was something like 200 years after Cornelius and Zira that the dogs and cats died, humanity turned to and domesticated all sub-species of apes, increased their intelligence, and took them on as pets and then slaves, and then the events of the movie take place with the uprising of the apes... in just ONE TENTH of the time indicated by Escape!

Jarring timeline discrepancies, there!