I think the UK telecoms market has much lower headline prices thanks to the sheer number of MVNOs (virtual networks) - regular operators even own MVNOs to get some brand segmentation (Three owns Smarty, Telefonica O2 owns GiffGaff, just to name two).

The MVNOs compete heavily on price, and drive prices down for savvy customers. You can get 3 GB/month with unlimited calls and SMS (with roaming to 50+ countries) for 6 GBP per month on a 30 day rolling deal, right now.