Two kinds of FTA. The legal kind and the hacker illegal kind.
The legal kind is where someone purchases the equipment and sets up a dish to receive any of the hundreds of channels that are broadcast unencrypted via satellite. It's just as legal as putting up a rooftop antenna to receive locals instead of paying for lifeline cable.
The illegal kind is where people take these receivers and load modified software that illegally decrypts encrypted pay television. That is against the law. Most of the people doing it are so stupid that they brag to everyone about it or they post on a public forum that they do it.