Flew 2 R/T's domestically in USA with S&S bike, IIRC once was on JetBlue & the other maybe Delta or United. Didn't get charged a bike fee. AA & United policy seems pretty clear about not charging bike fee for S&S luggage, Delta is weirdly ambiguous. I'd avoid Delta if it wasn't too much expense or trouble but I'd reckon the check-in staff are more usually more concerned with moving the line along than hassling over dubious S&S fees.

Impressive to read how Asian airlines treat bikers nicer than US or Euro. IMO airports & airlines should have a co-op reasonably-priced rental system for sturdy bike crates. Eliminates waste of cardboard disposable boxes & allows bikers to ride in/out of airports.