Agreed.

Also I think that if you live next to a warmongering country you certainly care more about making a military invasion the shittiest and the most vile thing for the aggressor that you can think of and landmines are cheap and effective there.

I think it's a sufficient trade off that landmines self-disable themselves in, say, 5 years or so. If the war continues you'll keep planting more and when it ends you'll just wait a few years and go collect them.

You don't just collect landmines though. The Germans in WW2 had maps which they handed over to the allies but it still killed hundreds of people clearing the landmines. Eventually they decided to use German POWs.