Madison is exceptional for a midwestern city. It has a large and excellent state university. Epic is based there and most of FAANG has outposts there to draw the CS talent. Additionally, it is the state capitol which means a lot of companies providing services to the state. Aside from all that, it is a pretty picturesque location for the Midwest, with the two big lakes and surrounded by rolling hills. Something you won't find in Urbana-Champaign for comparison.

When people talk about low cost of living in the Midwest they generally mean more depressed areas. I live in a very low cost of living rural (15k ppl) community in Illinois, with half an acre on a lake in a 3000 sq foot house where the mortgage is only 250k. Of course, if I ever lose my remote job, I'd never be able to find work. Most of the people here work at one of 2 medium-sized factories or the hospital. The median household income is only $40k.

The town I live in is a far more common case for the rural Midwest.