The other posters have added many good comments.

Just want to add one small one: Since airlines began to print the "customer status" (in airline industry mostly: blue/base, silver, gold, black) on the boarding pass and began to issue "privilege bags" people have begun to tell all (un-)related others how important they are.So if you look at airports most of the people use that privilege baggage tags for their hand luggage where they are really senseless (except showing the status).

And with the cost cutting in many industries and the restriction of acceptable service (which in former times enjoyed EVERY customer) levels to own top customers people where educated to show how a large customer they are !

In credit card industry:
So everytime telling someone they have the "black" card they feel a bit more self-conscious and don't think about the enourmous yearly fees, people pay only for a perceived value @:-).

I have seen many coulours of Amex work, the Blue, the Green, the Gold, the Aurum (discontinued) ones, the co-branded ones, the Platinum,... and except from some perks like invitations to [sales] parties ähhhh very exclusive shop openings restricted to a very small number of those who are beauty and rich the basic principles and services are the same !!

So just mind which coulour anyone has, because in case of a phone order you don't see the card in reality. In my own point of view these different designs are interesting in respect of a kind of "artwork" and style...