The Guardian takes a nice look at the hot spot market in the U.K.: Just like in the U.S., operators there are playing with different ways of offering service. One provider, Broadreach, always puts PCs in its hot spot locations so customers can use the network without bringing in their own laptop.
One difference in the way hot spots work in the U.K. compared to the U.S. is T-Mobile's deployment. At Starbucks in the U.K., customers who aren't regular subscribers must buy a voucher from the barista to use the network by the hour or day. The vouchers expire if customers don't use them within a time frame. It seems this process discourages use.
I wonder why T-Mobile doesn't just set it up like in Starbucks in the U.S. where you can buy a day's use online? Maybe in the U.K., it's an issue of people using credit cards and their comfort with making online purchases.
I don't think it's a comfort issue. The kind of people who are comfortable surfing over a Wi-Fi connection in a cafe are probably going to be all right with making an on-line purchase.
I think it's more likely to be a systems integration issue. T-Mobile in the UK has a different history from T-Mobile in the US, and in Germany for that matter. They've probably got different technology partners and suppliers. My guess is that this is just approach that was chosen locally - maybe provisioning with a voucher was simpler, or the fact that it is bought through the barista means that it is easier for them to monitor sales.
I think you got a few things wrong there on how it works at T-Mobile/Starbucks in UK. The option you have is to by online, through credit card, unlimited access for one hour, 24 hours, 1 month or a 120 minute bundle used at any time within one month. There are no physical paper or plastic vouchers involved unless, I guess for promotions.