Raven Crowking
First Post
No, it's not a static difficulty because you have to rely on the d20 which generates a random result. A person with 10 is slightly above average while a person with an 18 is almost an expert. There is no take 10, therefor there's no automatic or instant success.

I fear that you and I are talking two different languages here. Let me assure you that, when I say a "static difficulty" I mean that the level of difficulty does not change. That is, the numbers represent the inherent difficulty of a proposition, not the ease with which certain characters may approach that inherent difficulty.
Usually, this is simulationist in nature. A monster whose hide is equivalent to plate and shield in AD&D 1e is AC 2. It is AC 2 if the PCs are 1st level; it is AC 2 if the PCs are 15th level. Likewise, a basic lock needs no description; the "DC" is the baseline thief's chance to pick locks. All the DM need do is define harder challenges (say, -10% to pick locks) or easier ones (say, +15% chance to find traps).
The converse of this is a system in which the difficulty of picking a lock is not based on static chance, but is based on an ideal idea of how often any given PC should be able to do it. So, if the goal is to have you find 50% of all traps, the DC of locating traps should be 10 + the searcher's bonus to the task. Or, for example, the AC of creatures should depend upon their CR rather than their description.....try to make the description match the CR!
All characters of the same level, ability scores, and skills are always equal in capability.
All characters that are exactly the same are exactly the same. This, at least, we agree on.

RC