That’s always sort of interested me.
Why should religion exempt someone (even the Amish) from our laws?
If my religion says it’s ok to sacrifice virgins, should that be tolerated?
Waht about the Mormons and bigamy?
It's a bit of a patchwork, but goes back to honoring the pacifism of Quakers as against the power of the state to compel militia duty, and now, the draft.
As you point out, other religious practices (polygamy, human sacrifice) do not obtain protection. Since the government makes the laws, it gets to pick where it draws the line. Some religions are exempt from drug laws (indians can eat magic mushrooms and cactus), tax laws attempt to avoid houses of worship, etc.
I find the area of government vs., religion to be one of the most fascinating to study (reading the cases) because the ultimate rationale for the decisions are telling of cultural bias.
Amish do not pay social security. They have an agreement with the feds that they will take care of their own. I don’t know about Medicare but I bet they don’t pay that either.
They don’t pay property taxes because they rotate the meeting place for religious services around every household.
They also make a moderately good living because although they don’t farm many acres they also don’t have much in equipment costs.