Good point, Joe.
Blanks are covered against breakage/defects from mfg - IF the blanks has never been cut down. Custom builder has to eat his labor on the rod and some components, too. Some builders factor that into their costs.
Unfortunately if you snap the top of an 2 pc rod - it isn't as simple as getting a new top very easily. Tops are fitted to bottoms and there are some variations.
I haven't had to deal with rod warranty on factory rod yet. I popped out the guide to my St Croix Premier 8.5-2pc a month after I had it - I superglued the ring back in and it has been that way for a couple of yrs or more. I could re-wrap it, but won't bother until it breaks again. I have plenty of other rods to use as back ups.
About 24 yrs back my Dad slammed his trunk on the middle of my brown fiberglass Fenwick PLS65 and I sent it back and then sent me a brand new one.
Not sure how they are now ..... lol. Same deal w/ HMG spinner - tip snapped off and they gave me a new rod. Downside was they were newer models and I liked the older designs better.