Cash... really?

I got myself a cell phone for Christmas this year. Nothing fancy... in fact, it's one of those old school jobs. (Yes texting takes forever without a slide-out keyboard).

So as you can expect, I revived my first bill. I went in to pay said bill at the Kiosk where I originally bought the phone.

After buying a USB cable for the phone, I tell the clerk, I'd like to pay my bill. He then informs me that I can't use cash, I have to use a credit card. I'm underage (gasp!) and hence don't have a credit card... so I have to find a place in the mall that sells a Visa giftcard. I found one, bought it and went back to the Kiosk. I'm then informed that it takes these cards 30 minutes to activate, but I can go home and pay over the phone!

So in review I can pay my bill --

Over the phone by credit card - Over the Internet by credit card - By auto withdrawal - By manual withdrawal (I tell the bank to pay it) - in person at the Kiosk, but I CAN'T pay with cash... why?

They do take cash for accessories (remember that USB cable?), but when I want to pay my bill, I can't use cash? What's the point of having a currency if we aren't going to use it? I'm not too crazy about auto withdrawal and I likely wouldn't get a credit card for a little while... but I always carry cash! Maybe I'm over reacting, but it seems really illogical to me that I can't just hand the guy 30 bucks and be done with it... I don't mind using Visa giftcards, the only catch is the extra charge for activation.

Can you relate or am I just overreacting?