To geek a little about the topic, Orson Welles was largely just reintroducing an active camera as it had been in many late silent films like "The Crowd." The early sound era really locked down the camera for awhile, due to the size of early sound rigs, and he let it loose again, with a few unique spins of his own. Or something like that.
A.P. also liked to put his name on the copyright of the songs he collected, not unlike later practitioners. Still, they're one of the bedrock musical groups of America, with wonderful harmonies that still resonate through plenty of the music of today. They played the hillbilly, but they were a fully modern, urban, commercial enterprise, and I'm sure there were naysayers even back then deriding them for being "fake country". But there was nothing fake about them. In addition to the records, it's great to hear some of the CDs of entire radio performances, like the amazing transcriptions they did for the semi-legal Mexican border station XERA in the 30s. These border blasters were many times the power of licensed US stations and could be heard over half the country -- a huge audience for the Carters and many others.
People forget that when Johnny Cash married June Carter, it wasn't her that married into royalty; she'd been performing with A.P., Sarah and Maybelle since the 30s. Her mother, Maybelle, is one of the top two or three folk guitarists that ever lived.
Carter Family were great, but they were not the first American rock stars. The Hutchison Family had to be snuck in and out of venues in the 1840's in order to avoid screaming, adoring fans who had shelled out up to $130 in 1840 currency to hear the four part harmonies.
People forget that when Johnny Cash married June Carter, it wasn't her that married into royalty; she'd been performing with A.P., Sarah and Maybelle since the 30s. Her mother, Maybelle, is one of the top two or three folk guitarists that ever lived.