They are already charging as much as the market will bear
As Telcos discovered, they only advertise a base price. If you ask for the full price you'll owe, they wont tell to you. You'd need to be a lawyer and read the 15 pages of fine print to figure it out. Then, you get stuck in a 2yr contract, get the first bill, and discover all sorts of things like the "Regulatory Recovery Fee" and the "Emergency Surcharge"
Source? While I agree the advertising doesn't prominently display the all-in price, claiming that you need to be a legal professional to figure it out is a bit hyperbolic.