Ever since I was a kid, up until now that I'm middle-aged, I've always wondered why, in wars or otherwise, they bother digging down mines which explode when humans tramp on/near them. This seems like such an insanely inaccurate, indirect, devilish and, most of all, stupid way of going about things.
The obvious main problem is that not all the mines will be stepped on/explode during the war. Another obvious problem is that your own soldiers, or civilians, will accidentally step on them, during or long after the war.
It just seems stupid to me. If you are going to put them down, at least limit them to a specific place and in front of an important stronghold that you suspect will be attacked, to stop the enemy. Preferably mark it as a mine field very clearly, and make sure to sweep it after the war, or at least leave records of where the they were put down, so that others can do it later.
It seems like a ton of work and risk for very little reward. Those mines aren't free to invent/improve/manufacture/dig down/keep track of/deal with later, either.