Hardly a 'leader in an issue' - Amber turn signals are required on all vehicles in europe, and despite what many think, the european car market is bigger than the American one - UK, france, germany spain = USa, ireland = canada, then you have portugal, italy, etc.
When cops in the Uk are in a strict mood (say around a 'cruise' they'll get you for fog-lghts, and if you've got red indicators 9or white, when applied) you've evither got the choise of fixing it without moving the vehicle, or towing it, since technically its unroadworthy (UK drivers tend not to look for red turn signals0 and often they'll tear up your MOt certificate, and force you to get another.
Its to do with joe schmoe, and what he thinks is nice. just look at TV, and you'll see just how much taste the average american is deemed to ahve.