I have lived near several Amish communities and each community seems to set its own standards when it comes to contact with the "English" in the city. Some of the
Amish in southern Missouri will ride in someone's car if that person will agree to take them to buy groceries, but they of course will not own their own car. I have seen them shopping in supermarkets, so they are very familiar with the wide variety of goods available, the Amish I observed confined their purchases to bulk staples such as big bags of beans, flour etc. Of course, their contact is limited. I have seen them downtown in some small towns, or at large strip malls or supermarkets--no parking meters in either location.
That community also provided crews for contractors. The Amish seemed to specialize in roofing, and they were quite a contrast to the non-Amish working with them. The city guys would work stripped to the waist, but no matter how hot, the Amish men did not doff their long-sleeved shirts or hats. They arrive at the job all riding in the back of the contractor's truck. I suppose that there are really strict communities that would refuse to accept rides in trucks or cars, but these Amish seem to have found a practical compromise. As for school, the southern Missouri Amish send their children to school up through grade six. They ride to school on the yellow bus, but do not participate in computer classes, and if the teacher shows a video tape, they turn their backs to the tv screen to avoid watching tv. I was a teacher in one of these schools but that was 25 years ago, so they may have loosened up some...or not.
In central Missouri there are several communities of Amish that are involved in dairy farming. These groups have also developed some interesting policies. They depend on sale of milk to dairies for income, but ALL milk sold in Missouri must be milked by machine, pumped to large refrigerated holding tanks, and then transported to the dairy in collection tanker trucks that come to the dairy. All of the milk transporting/handling equipment at the farm must meet the same requirements for cleanliness, refrigeration, etc., as the health department sets for the dairies themselves. So the Amish in this area have electricity for their cows and their barns, but their homes are lit by kerosene lanterns.
Some will operate stores to sell their quality furniture, or arts and crafts, or homemade jams, jellies, bread, etc. These stores also need electricity (and probably a telephone) to operate.
I try to remain open-minded when I meet the Amish around here, but it is hard to think of them as just another religious group. They do stand out in a crowd! There is one time, however, when it is difficult not to cuss at them--and that is when I crest the top of a hill on a two lane road driving 60+ mph and then--right there in the road is a damn horse-drawn buggy going about 3mph.