Earlier quoted context omitted.
Which is exactly why they should be banned to keep the market overall healthy. Preventing deceptive practices in a market economy this is a prime example of useful government "intervention", just like supporting contract enforcement or preventing theft
They can always justify it as not knowing the price. The sales tax rate is different in different places. It costs a different amount to ship to Florida than Alaska and picking it up at the factory is free (even if nobody does). The advertised price is if you have your own modem, renting one from the cable company is more. None of these are inherently wrong. You should be paying more if you're having it shipped to a…
You could as easily say that the marketing department not knowing the features of the product justifies them making whatever claim they want in an advertisement. Why should a company be permitted to advertise something they don't know to be true, let alone something they know to be false?