Contact with the Modern World
Connectivity and contact are more normal now, so those communities that kept to themselves are currently dealing with more modernity and people. The New Order Amish have taken to using pagers and cell phones, but Old Order Amish still refrain.
Not Many Choices
The Amish are required to marry within the community, which is limiting. Though you can’t marry a first cousin, it’s possible to marry a second cousin. Lancaster County doesn’t allow marrying a “Schwartz” cousin, which is your first cousin once removed.