The way I heard it explained -- they prefer to avoid any technology that leaves them too dependent on others outside of their community. Otherwise the outside

The way I heard it explained -- they prefer to avoid any technology that leaves them too dependent on others outside of their community. Otherwise the outside can have some influence / control over them, instead of being self sufficient. These rules can be relaxed where safety is concerned (i.e., lights on their carriages, refrigeration for the milk), but the lights are powered by batteries that they charge on the farm (from the diesel generator that is used to power the milk refrigeration).