Some of their power equipment is pneumatically powered with diesel driven compressors. I also read about a hydraulically powered shop.
You're right. The more conservative groups still use line shafts to power their machines and forbid the use of air nailers. The nice thing about hydraulic power is that it gives every machine variable speed without a loss of power, but they spend a lot extra to convert their equipment initially.
The rules vary a great deal from church to church and change over time.
I heard a funny story about a Lancaster PA farmer. He was in his barn talking to one of the ministers of his church. Suddenly a cell phone rings. He says to the minister, "I guess you caught me" as he reaches into his pocket to answer. The only thing is that it wasn't his phone ringing it was the minister's.
That's funny. When you hear stories like this about Amish going around the rules you wonder: "Why don't they just get rid of their silly rules if they don't want to obey them?". But I suppose it's just like guys who use radar detectors in their cars. They are like us in a lot of ways.
It used to be that they could easily tell if someone was cheating. Power lines, telephone lines or TV antennas were a dead giveaway. But now with lithium batteries, DVDs and buried cable it's harder to tell.