The different groups have different rules, someone wants to do something different but their current group doesn't so they splinter off creating a group that allows the thing (sorry if you already know this)

For example, Ohio Amish don't have the same rules as Lancaster/PA Amish. How the buggies look is dictated by the group they belong to

Years ago I recall reading about a group in Ohio that's so strict about electrical use that they don't even allow electricity for a well pump, instead they use a horse hitched to a mechanical device to pump the water