They asume that you will either go over your minutes, or (MOre likely!?   ) forget to claim the cashback.

I ran a Nokia 3330, then a '3' clamshell thing & am now on an Orange Motorola V545. Has not cost me a bean (other than calls from/to abroad when on hols) - 200 mins/month + rollover & 4Mb of WAP (or whatever it is - never use it).

Then you can flog the phone after a year & make a little on the deal!