Take a look at the limtation on the Trek warranty and you'll realize they can ding you for just about any replacement you try and claim against.
2 year cover on Bontrager forks and swing arms on FS models.
3 year coverage on their dirt jump and DH models (most likely to take the highest abuse)
phrases straight from the warranty:
■Improper follow-up maintenance
(Can you prove that you didn't over-torque that bolt? I bet Trek's engineers can prove you did.)
■Installation of components, parts, or accessories not originally intended for or compatible with the bicycle as sold.
(P-clipped some fenders on your CF roadie rig for a rainy century? Maybe just used some Speed-EZ? Yeah, you've voided your warranty because your racing rig was not intended to be used with those accessories.)

I'm sure there's some stories out there about companies with lifetime warranty going above and beyond for someone making a claim against a 25 year old steel bike that snapped a weld, and they offer some kind of massive discount on a replacement frame... but I'm guessing the more likely case is they'll lawyer up to save themselves a few grand by finding some miniscule reason not to honor the claim.
Specialized waranty states that you must have proof of sale that identifies the bicycle by serial number. Do you have a receipt with your bike's SN printed on it? They also disavow any need to replace bikes which have been damaged by "riding in severe climates" (does a PNW winter with 6 straight months of riding in the rain count? I'll bet it does) or "with heavy loads" (another vague statement. How heavy is heavy? 25 pounds of commuter gear? 60 pounds of touring equipment? I'm sure their legal team will tell you the specific limitations when you file a claim.

BD catches a lot of undeserved flak for their perceived wrongdoings against brick and mortar shops and for supposedly sullying the brand names they purchased.
Pffft. Whatever. I didn't see any effort on their part to "hide" the CF warranty coverage. It's spelled out plain and simple on the left side of the Motobecane warranty page, along with the coverage for their other parts.
If I look to get a CF bike in the future, BD is high on my list of places I'd purchase from. I've seen quite a few of them on club century rides around here, and a few people with my rando group ride full CF BD rigs for brevets.