Daggerfall was as level scaled than Oblivion if not more.
Morrowind had level scaled random monsters, NPC was not scaled.
Fallout 3 had level scaling much like Skyrim, Skyrim has an system where npc get an bonus to damage and probably armor you don't get, this is to compensate for gear, avoiding the bandits in glass we had in Oblivion but on the same time keep them dangerous, NPC in Morrowind was mostly an joke on higher levels. Do not think this was done in Fallout 3.
This explains why bandits with good weapons are so dangerous.
New Vegas has no level scaling in general, I wonder if stuff like the legion hit squads who hunt you are scaled as they are very dangerous even at level 50.
New Vegas also shows the downside of no level scaling, you have to have an leveling area, in short you have to go south, east and then north to come to Vegas.
Also the area around Vegas get very easy once you have done some DLC.
It sounds to me that they have ramped up the difficulty a bit from Skyrim in that hard areas are harder than before as in hard.
Now two ways to do level scaling without leveling up the enemies a lot is :1 add more enemies, this is doable now, 2 if repair is still in use weapon and armor condition to make enemies more dangerous.