Fallout New Vegas

That's simply not true. Look at Caesar's ending outro.

The Legion occupied all major locations, enslaving much of the population and peacefully lording over the rest. Under the Legion's banner, civilization - unforgiving as it was - finally came to the Mojave wasteland.
After the Legion's victory, Caesar, out of a strange respect for his old fellows, allowed the Followers safe passage out of the wasteland. Reluctantly, the Followers accepted the offer and abandoned Old Mormon Fort to the Legion.
The Legion, preoccupied with its acquisition of New Vegas, scarcely took notice of the town of Goodsprings. Many locals moved on, fearful of Caesar's long shadow. Only the old and the stubborn remained.
As reward for they loyal service, Caesar forcibly integrated the Great Khans into the Legion.
After Hoover Dam, the leaderless Powder Gangers at the Correctional Facility vanished into the wastes, leaving the prison empty.
Though Caesar keeps Primm open for business, its citizens live under the constant watch of Legion soldiers.

...and that is with an evil karma. With good karma and depending on the player's choices, some factions have an "easier" ending (fleeing west instead of fighting and losing to the Legion).
It shows that those who surrender to Caesar can continue their lives with more stability and without the usual constant danger of the wasteland.
Roads are safer and some people still keep their autonomy.