Private mail services

[Grunty]

One of my regular bills comes in an envelope marked TNT Mail, but is delivered by the Royal Mail. How can these two organisations afford to handle the same letter and presumably make a few pennies?

[Kos]

http://www.postcomm.gov.uk/postal-licences-and-operators /licensed-postal-operators/tnt-mail-uk-limited-formerly- tpg-post-uk-ltd.html