It's unlikely anyone will be able to explain this to you with proof out of the code, but experience can explain a lot.
When coh1 first came out, they promoted the destructible environments heavily. This is important because I have an opinion that I have never been able to prove true, but it describes the activity in the game.
Something deep into the way they program coh or maybe it's engine, Essence sends ordinance at certain things with more affinity. These are "accidents" as seen by players. The issue with your mines are just part of a larger phenomena you will notice if you pay attention.
Others are:
- Plane crashes
- engineer squad types
So what will happen with planes is that the game will calculate hits on the plane such that it can be placed on a trajectory with player or world objects. I know it sounds conspiracy theorist, but keep in mind that it got so bad in coh2 that we had to make plane crashes not cause damage to player objects. Of all the places planes could crash, the game likes to send planes into objects, instead of crashing the plane where there is nothing.
Why is this? It's because of what they promoted earlier in destructible environments. They want the player to have that epic experience where all kinds of stuff happened in the destructible environment. In your real life experience, you likely did not see real random events go down like this. There have been accidents in your life. You've seen someone lose control of a car, or a bike, or maybe just trip. IRL the common occurrence is that the car crashed in a ditch or maybe hit a gaurd or pole. If Essence controlled reality, most cars out of control would get sent into crowds of people, traffic, or into store fronts(full of people).
Pay attention to the plane crashes in your game. You will see most if not all crashes intersect with some object. Not just grazing or a near miss, things get nailed perfectly.
The game also likes to kill engineers. I'm not sure why this is, it's really strange, but engineer units attract extra fire. This comes in the form of missed or stray shots which just so happen to hit the squad members. You can see some proof of this bias when you play the AI. Watch how the AI behaves when in relation to your other infantry types. The AI will take risks to hunt your engineer units, but will avoid all others. This is true regardless of faction.
Coming around full circle, let's talk about mines. The game sends stray shots into mines. In order to do this, the stray shots need to be in the scatter zone. Any missed shots will prefer to nail the mine, this affinity increases if you are fighting on the mine. I've seen it time and time again, because I place a lot of heavy mines with the m20, but it also happened a lot in coh1. It happens more in Coh2 though. If you fight near a mine, the game will send the misses at the mine.
I expect most will see me as crazy, but remember the now 0 damage or 1 meter area plane crashes, because planes keep "happening" to fall on squads over and over. I've had to completely change my tactics for mine laying over time to make sure that I don't have fights near critical mines. I've had so many instances of missed panzer 4 shots getting directed at the mines, then the player escapes what otherwise would have been a lost tank.
Teammates would come to my mine fields to "help" and sit on the mine to fight. Usually with their most expensive unit. Next time I look, there is a smoking mess or a disabled tank, dead blob, w/e. If you fight directly on the mine, anything that damages your vehicle will typically cause damage to the mine too, so don't do it.
TLDR: stay the fuck away from your mines after you lay them