Because they can. NYT:
Professor Keshav estimates it costs the carriers about a third of a penny to send text messages. Considering that the major carriers charge 10 to 20 cents to send and receive them, “it’s something like a 4,090 percent markup,” he said.Interestingly, Apple will be releasing a messaging software that lets you send text, video and photos via your data line or wi-fi for free. Should be interesting to see if the phone company is able/willing to block it somehow.
At 20 cents and 160 characters per message, wireless customers are paying roughly $1,500 to send a megabyte of text traffic over the cell network. By comparison, the cost to send that same amount of data using a $25-a-month, two-gigabyte data plan works out to 1.25 cents.
