Numbers like that are almost always the same story. I wasn't familiar with that exact battle [1] but it also matches the pattern. It's not like the peasants actually took on the soldiers, but rather you had some peasants inexplicably leave a town, and organize themselves within a circling of wagons, a 'wagon fort'. That wagon fort was then fully encircled, and 'ambushed' starting with artillery.

The peasants immediately broke and fled, which is where you get the crazy ratios from - fleeing armies are extremely vulnerable and near harmless. Had they fought, they likely would have inflicted far greater casualties on the military forces. However given there were roughly comparable peasant and military forces, the outcome was not in question, so it would have been suicide. Of course so was fleeing.

[1] - https://en.wikipedia.org/wiki/Battle_of_Frankenhausen