Well, no, not all the inspectors are SCTA, no matter what event -- at least not in the past. As far as I can tell, here's some of the story for WoS '04:
Dan Wright used to be the chief inspector for USFRA, but since he's building a car this year he didn''t inspect. Henry Louie used to inspect for USFRA and SCTA, but last year I heard his eyes were giving him trouble and that he wouldn't be at the Salt this year (sure enough, no H.L. in '04). Last year USFRA had Jim Burkdoll doing some bikes (he was the second inspector on mine in '03), but not this year. So I was kinda wondering who we'd find -- and lo and behold, there was Tom Evans, the Chief inspector for SCTA, wearing the yellow USFRA hat at WoS. He did the first lookover on mine, then Dan Warner (another SCTA guy) did the second look.
I don't know the in-depth story of why SCTA guys were there, but probably am safe in assuming that USFRA requested some help from SCTA. As for variations in rule-enforcement/strict following of what's printed vs. what "you were told" -- well, you shoulda been at Bub's where the inspectors used lines like "Well, we'll let that go, even though we were kinda anal about it on a few other bikes before yours." Really!
I'll say it again - I like the inspections at ECTA. Nobody - NOBODY - gets cut any slack, whether it's safety wiring something that the individual presenting his bike thinks might be good enough without the wire but the inspector insists must be done to the book -- to leathers -- to requiring me to put locknuts on the adjustable steering stops because the screws might back out and allow some nasty headshake from getting out of hand. I look at the inspectors as people there to protect my butt -- heck, I TRUST that that's why they're there, and hope that that's what they're going to do by enforcing the rules.