What exactly is keeping you from enacting your plan exactly as advertised? I'm genuinely curious.
Maybe you'd need some special kind of strip club zoning or something? Because it's legal for people to take their clothes off there, for money even. And I guess there's some requirement for that kind of thing to not be visible from the street, so you'd have to cover the windows, too.
That you might enact the changes and immediately lose most of your revenue is beside the point. If city hall gave you the necessary permits 'n whatnot, it would be your prerogative as a business owner.
To address your original argument, the legality of contracts has been a field for a very long time so apparently somebody somewhere is watching the system and wants it the way it is. Phone companies can put all the shit they want up on the screen in fine print. Not calling them on it is implied consent on the part of the regulatory agencies.
So I guess my point is that when you said, "I can't just put up anything I want and have it be legal," yes...yes you can, if you're a telecom company and nobody calls you on it. That's the pragmatic truth.