The Optimized Party?

[Curmudgeon]

Explain then, why Epic Trapfinding exists if the function is automatically available for Rogues anyways, and Rogue is the only class that can qualify for the feat within SRD rules in the first place?

Ah, thank you! You've found the explicit statement of how Trap Sense gives automatic Search checks. You see, Epic Trapfinding is actually a 3.0 feat named Trap Sense (Epic Level Handbook page 68). In 3.0 the Rogue didn't have Trap Sense as a class ability. The only update the feat got in the "FREE D&D® V.3.5 ACCESSORY UPDATE: Epic Level Handbook" is the name:

Two epic feats have received name changes. Beast Companion is now called Magical Beast Companion (see below), and Trap Sense is now called Epic Trapfinding.

Interestingly, the official online feat index still shows this as Trap Sense. It's redundant for Rogues, of course, but exists now for classes like the Beguiler who can eventually attain the same capability Rogues get at 3rd level.

As a note, the difference doesn't exist in PHB; both Barbarian & Rogue have the exact same ability.

Then both classes with Trap Sense should get automatic Search checks for traps. Without Trapfinding the Barbarian is limited to traps with DCs of 20 or lower, of course.