Mobiles are expensive thing in UK
The mobile charges in UK are just too expensive, it cost a huge portion of wages. As I knew, in South Korea, Japan or China, mobile charges including Internet surfing, a giant amount of call minutes (even unlimited) only cost half day's wage in average. But, in UK, it's quite often that you may need to spend a whole day's or even 2 day's wage to pay for a limited amount voice call minutes.
In some cases, the providers are just want to bound their customer with contracts and force them to purchase their handsets.(You never get a suufficient amount of minutes with pay as you go)