You make some excellent points, and raise a good question. I agree completely; that a reasonably experienced, well-trained aviator with the proper mindset should clear initial and be able to follow it up with a successful upgrade relatively soon. But with the exception of a few at Lakes who meet that criteria, that isn't the case.
Many of our newhires are downright dragged over the finish line during initial, gasping for breath, instructor tugging by the collar. Low-time guys hurried through an atrocious ground school (ambifurcated plenum? narsuls? They're making up new words) sent to briefly wrestle with an unflyable sim where weight lifiting is more valuable than decision making, then put in the right seat of the aircraft at 3am after bouncing around in a cabin seat for the preceeding six hours, pissing in a bottle...it's a hell of a month, where they learn alot but not nearly enough. "You'll figure it out on the line." Hopefully. Maybe.
These horrors are remembered from the first time through, and they know the standard will be higher during upgrade, after all that's the threat they were browbeat with during initial. Imagined or not, they know it's gonna suck.
And heck, it isn't the upgrade training or even the checkride most fear, it's the arcane written pretest that must be passed on day one to proceed with training. Everytime the test is updated, 80% of the first batch fail it and go home.
This place is completely dysfunctional. A culture of fear instilled at every turn, CRM trained out of crews, a focus on the irrelevant. Someday a crew is going to auger into a mountain while fretting about why the D.O. just left a nasty message on their voicemail. Just a matter of time.