"They also buy things from non-Amish sources like grocery stores, convenience marts, and superstores like Wal-Mart and Costco."

https://www.dutchcrafters.com/blog/6-things-you-might-not-know-about-the-amish-and-money/

That's why you can see them in towns with their horse-drawn buggies. You think they just want ride into the city?

https://amishamerica.com/images/various-small/walmart_amish2_2.jpg