The reason is their rigs aren't that complex. I mean jeebus just read the butthurdt that goes around this forum alone if you do anything
other than Pre-DI!
Chris and JC got those vids b/c they were done by Dunlop AND they have massive, big, complicated rigs and in their bands, the bass is arguably the biggest factor of their even bigger and world-renown acts.
And lol at the posts above that "everyone can learn from someone"- I"ve been on TB almost 9 years, and just read most daily Page 1 posts in any of the subforums and you'll learn that's not the case...

:facepalm: Unless you want the best " " for "metal"... There's plenty of noobish and not very good reviews here and on YT alike, which is why like the OP, I'd love to see some vids from people who matter OR their techs who do this professionally.
Rex has a mini runthrough of his old Down rig that's around. Mark from Breaking Benj too.
But however as stated, most live rigs for popular artists would maybe take 30 seconds to go through with how simple/basic it is.