That's not DSL, it's "Uverse". And it's not "cable" (i.e. coax), it's twisted-pair phone service.
In a nutshell, traditionally there are three types of wire carrying three different services: power (large braided steel/aluminium/copper), phone (24-32awg copper pair), and cable (coax) Thanks to modern technologies, all three can be used to carry data ("the internet".) Thanks to additional technologies, both phone and tv are now "data", and thus, can be fed over any of those common wires. However, the point remains -- You have ONE power utility, ONE phone utility, and ONE cable utility. You don't have 5 power companies, 19 telcos, and 17 cable companies spidering various cables all over creation to millions of consumers. In the "last mile", there is very little competition. If you want to sell me DSL, you WILL be paying AT&T, because they own the local lines.