If you go online and check out each of the four major carriors, all their plans are pretty much exactly the same. They all charge relatively the exact same prices for everything. The only differences between them are what phones you get to pick from, the contract length, and which part of quality you want. Remember, you can't get both good quality signal and no lost calls. You can't get both full bars everywhere you want to be and some bars everywhere else.
Some of them have something a little special like rollover minutes or the ability to call a certain number of people outside their network(under very special circumstances), but it's more about who you know in each network and not what they offer or what they cost. I have Verizon because all of my family and friends are on Verizon. This means I can call everyone I know for free. But the fact is that with normal competition, prices should have fallen by now and they have not. It doesn't cost them $5 to send 100 text messages but that's what they charge me.
It's like two gas stations across the street from one another. They could get into a price war till neither of them makes any money, or they could silently agreed to charge the same price and split the customers. Next time you see two gas stations across the street from one another, notice if their prices are the same. Unfortunately for most of us, we can't just drive down the street to find a wireless company that isn't silently price fixing.