If there is nothing wrong with carrying on a conversation at a restaurant table in person, why would it be any worse to speak in the same tone of voice and volume into a cell phone? If someone talks so loudly to a friend in person that their voices are annoying to other diners, that would justify managerial instructions to lower their voices to an appropriate volume.
On the other hand, why would an appropriately quiet conversation on a cell phone be more annoying than a normal conversation of the type ordinarily permitted between diners? Similarly, in the example given by the store owner in the article, the cell phone user whose conduct precipitated the ban had held up the line of customers behind her to finish her phone conversation. Would the same inconsiderate behavior have been perfectly acceptable if she had been talking to a friend in person instead of on a cell phone when she refused to conduct her transaction at the register before finishing her conversation? Would the store owner have been right to ban all conversations in his store as a response?
The problem is one of perception: specifically, the fact that people seem to exhibit more obnoxious behavior when they use cell phones than when they have in-person conversation.
But the solution is to address the volume of the conversations, or the refusal to interrupt those conversations to conduct business, not to ban all cell phone use across the board. Talking quietly and appropriately on a cell phone in public is no worse than having a similar conversation in person. It is a misconception that cell phones are the problem. The problem is not cell phones but rudeness.