"...treadmills were used as punishment devices for people sentenced to hard labor in prisons."[0] To grind flour, hence mill. But that is the useful version of

"...treadmills were used as punishment devices for people sentenced to hard labor in prisons."[0] To grind flour, hence mill. But that is the useful version of the concept. "Reverse treadmill" is what we should call the consumer product that cost emissions to produce&operate (simulate a "load" that needs to be pushed against by a citizen with no where to go). [0] https://en.m.wikipedia.org/wiki/Treadmill https://en.m.wikipedia.org/wiki/Treadmill