Problem with Indiana is that the land is much higher priced and they prefer to not pay that much for a simple family farm. Plus the incidence of tornadoes is much higher (per acre).
Still, the Mennonites have been settled in much of North central Indiana for a century and a half and have had a chance to influence the law to make the state tolerable for the Amish.
This gives them a choice ~ buy cheap and put up with Hochdutsche harassment in Wisconsin and the rest of the Upper Midwest, or pay more and be officially tolerated in Indiana.
No doubt it's a really tough choice for them ~ their money or their comfort ~ the Mark of the Beast is surely flashing before their eyes!
They have a pretty good business going over there. The entire town is a tourist trap with buses coming daily to gawk at them and buy high priced goods. You can check out the town here.
I call BS on your thesis of “upper Midwest harassment of Amish.”
I have family in and around the Shawano/Bonduel areas, north of Green Bay, who live in an around and among the Amish farms and the general air has been one of cooperation and respect. The Amish have been known and valued throughout the Fox Valley, and in the counties north of Milwaukee for their craftsmanship and and work ethic - I have first hand experiences with them working on repairing and restoring barns, and haven’t once heard a negative word said about them or their communities.
A few incidents does not a movement make.