"did they really tune some and not others?"
All Pythons received hand tuning at the factory. That was part of the extra work no other production gun got.
For an extra charge you could get a special order gun with even more tuning by a Master Colt gunsmith to bring it to an even higher level.
Colt still offers action or "trigger" jobs on most of their pistols, including Pythons if you send it back to the factory to the Custom Shop.
As far as I know they still offer two levels.
The "Service" level is brought to the maximum level that will still be 100% reliable with all ammo.
The "Target" level is to be used ONLY with .38 Special target ammo and will not be reliable with most .357 ammo.
These Custom Shop job will haver even lighter and smoother actions.