First, a common problem is that many photographs don't show bluing in a "real life" way.
It's not unusual for photos to show the finish as looking rather dull when it's not, and it's the photo that makes the above Python look like it has a duller finish.
Second, like everyone and everything else in the world, Colt Pythons bluing did tend to be less polished in later years.
Bluing at the Python level is almost 100% hand labor, and only the very best Colt polishers were allows to work on Pythons.
In later years, especially after the big Colt strike, a lot of the old Master polishers were gone, and the level of polish suffered.
The reason todays re-blues look like the old 50's bluing is because Colt is selling a re-blue job, not a complete gun that they have to try to hold prices down on.
Colt now offers several different levels of re-bluing, INCLUDING the "Royal Blue" which is the best bluing any gun company ever offered.