Why don't more sites use SMS as a form of payment?

I am playing around with Weebly now and I see they charge a small fee, only 5$ for some privileges. Last.fm has also a small fee for signing up(I dont know signing up for exactly what because I can listen to the songs for free already but that irelevant for this thread).

So a lot of sites want to charge small fees that I find perfectly acceptable. I want to pay for stuff, not because I like to give my money away but I'd rather pay a little for something great then get mediocre for free.

The problem is they all offer payment by creditcard only. I am resistent and so is a lot of other people to giving out my creditcard to the left or right. I don't want to have several different small fees everywhere that I can't keep track of. Isn't there some service for that btw?

Anyway, if they all let me pay by SMS it would be fine. I would buy a lot more... Am I alone feeling like that?

I don't know how charging for SMS works exactly when were talking Europe to an USA-based company etc. Maybe it is too expensive?

(an old thread about SMS-services: http://news.ycombinator.com/item?id=224324 )