In Hong Kong taxi drivers operate private networks known as "80% taxi's". You'll see many taxi's with multiple phones in them with different drivers operating on a few networks.
I managed to cut down the bulk in my wallet by 3 cards by photocopying the barcode side of my loyalty cards and sticky taping them to other cards which don't need to be swiped (nfc based transport card, nfc based car share card)
http://hk-magazine.com/article/inside-hk/mr-know-it-all/1145...