The modern trend elsewhere in the world is to use semi-permanently coupled matched consists for passenger service.
However, in countries that have extensive long distance service, at for the long distance trains the trend still is to have trains consists built of individual cars coupled together using standard couplers. Even there though because of other reasons e.g. braking system, HEP system etc. compatibility, more often than not similar cars from the same generation tend to be kept together. Attempts to keep cars with similar livery start with much fanfare at the introduction of a new service, but in five years it descends into a mess.
Matching the livery of train consists with engines is more often than not, mostly ignored.
As has been mentioned, operational convenience and cost considerations tend to derail the best laid out aesthetics plans. But it is still good to start at a good point.
The problem that Amtrak has is that, as Thirdrail and I have discussed elsewhere, it is a grossly under-capitalized operation, both on the capital purchases front and on the maintenance front. Under those circumstances, you basically acquire what you can at the lowest possible price, You maintain things closer to the point of failure than a fully capitalized operation would. The reason that the very effective maintenance paradigm used for the Acelas is not used elsewhere can be traced to this basic under-capitalization. Even when you plan to rebrand it takes so long to re-livery the relevant fleet that the whole plan falls apart and aesthetics suffers even more.
I am glad to see at least you agree with me. I have no idea what the real position of anyone else is.
