That's all well and good, but for an owner, you cannot have double standards. That IS illegal. Therefore the rules must be implemented for the weakest link and unfortunately, that would most likely be the abusers and users. A one man shop or even two or three, you can break the rules, but if it's found out by others..... your rules are then considered nonsense and deemed illegal. You'll be the one getting in trouble over some idiot on the phone just using up empty space........
On paper, that's true. I used to work as a manager for a company that employed 60ish people. When you wanted someone gone, you found a way / reason.
Good employee take a look at his cellphone and you don't want to punish him, but bad employees constantly on his phone? Well... bad employee now just got a Performance review about not getting the work done he should be able to get done. Is it becoming a problem again? Well... another performance review. You can leave the cell phones out of it completely, and get your point across / have ground to terminate if you need to.
Not every employee is treated the same, whether it's an employee at the bottom or at the top. I've seen managers / sales guys get away with stuff that would get anyone else fired, or at least talked to.