Quote from Skyjob:
"Traditionally the second tiller was a customer option, and moreover the legacy carriers have had them as experience in RHS was substantial, with limits imposed on experience prior to allowing its use from RHS."
My impression is that this is a long tradition involving US carriers - large and small - and US airliner manufacturers. No doubt it has spilled out into the third-world carriers as well, and smaller European companies that are inclined to buy the basic product as offered.
In the UK that included Caledonian Airways when they bought their first B707-320Cs in the late 1960s, prior to taking over BUA - which had a very different policy for its co-pilots. But BUA had an all-British fleet of BAC 1-11s and VC10s, not to mention Viscounts and Dart-Heralds - all with 2 tillers, IIRC. The merged company, BCAL, continued to expand its B707 fleet through the 1970s, with a mixture of second-hand 320C models from all over the place. The only ones I can remember coming with two tillers were ex-Qantas a/c, and the R/H tillers were soon removed in the interests of standardisation. For take-off, co-pilots operating as PF had to take control from the captain (without the benefit of rudder-fine steering) as the a/c turned on to the runway at fairly high speed for the Boeing-standard, rolling take-off.
Fast-forwarding to the present, I can't speak for the US, but how many European airlines operating divers types of Airbus have them with only one tiller? Most western airlines have a policy of complete role-reversal for handling and routine cockpit management. Maybe not a bad idea for the US to adopt the same policy, particularly if their skippers are going to continue as in recent days to drop like flies at the controls.