Okay, it's a high security area. What law allows them to prohibit the use of a cell phone? The way the US tends to work is that everything is allowed, except the things which are specifically disallowed by virtue of a law being written.

Think of it as whitelisting vs blacklisting. In the US we don't whitelist the things that are OK, we blacklist the things which are not OK. How did cell phone use in a border area get on the blacklist? If it's on the blacklist, but there's no law which put it there, then there's a problem.