Basically because they’re already there, as the following cool video demonstrates.
Having watched it however you should note that this sort of thing is only possible with a community that is homogenous and consistent in its beliefs about its version of civilisation, including morality and ethics, as well as being willing to support families in many different ways, especially in producing the number of men required to pull this off.
No Minister 
I live near Middlefield, Ohio. A rather large community of Amish have been in the area for a LONG time. Many of the community members take advantage of the natural gas that is below their lands. They would be pissed off if they can’t be like John Kerry and offset their natural gas use.
LOL
There are many varieties of Amish in this world – the canonical, movie variety who are very strict are the Swartzentruber Amish who basically adopt the technologies of the late 18th century which does include steel tools.
Indeed the Swartzentrubers are famous for their fine cabinet making which relies upon saws, chisels, planes etc all made from steel
And you can’t make steel in industrial quantities without coal.
When I was working in the US many years ago a close friend of mine had been raised as a Beachy Amish – this would be at the liberal end of people you might identify as being Amish.
He was still religious but no longer externally identifiable as one with Amish heritage.
We went to stay with his family in Indiana one time – it was pretty interesting
The house was plain but with electricity and electric lighting, electric stove but no washing machine , they had a pick-up truck, black with no chrome but most interesting of all was the telephone was not in the house but in a building like an outhouse. My friend Ken explained to me that these were the rules that that particular Beachy Amish community in Indiana had agreed upon at that time.
Would the world be a better place if we adopted the ways of the Amish? Possibly
Would that be possible – no