The law is not that you cannot carry more the $10,000 in or out of the country, but simply that you must declare it to customs when you transport more than $10,000 in and out of the country.
The frequencies that BPL affects are frequencies that allow people to talk all around the world, so the problem extends farther than just where the power is out.
Cell phones do not fall under part 15 of the FCC's rules. Therefore they don't have to follow this. I believe cell phones fall under part 22 or part 24 (but I could be wrong about this).