A nifty idea, but there are countermeasures a miner might take that are easy to implement.

a solution of solvent and typical mine explosive, either sprayed over the entire field of installed mines, sprayed over un-mined areas that you'd like to slow them down, or better yet, spray patches randomly over an installed mine field so that there are many false positives, indistinguishable from the tell of a real mine. Do all of these randomly so that a detection will require a thourough seach no matter what. Thats the whole point of a mine field anyway...

Edge a real mine field with 50 meters of false spots. Regions of false spots bordering regions of mines, randomly shaped and sized.

Encapsulate mines with impermeable skin... ziplok?

Saturate the ground with a persistent anti-microbial =)

Saturate only some of the field with anti-microbial =D

Now if you're a galactic civilization, the last thing you're going to do is be stupid enough to get yourself mixed up in that kind of a mess. All intelligent species would evolve with very strong competitive instincts
Exactly. Suppose you have a stable interstellar civilaization - a system that you've spent millenia to develop. You notice yet another young competitive race emerging, or atleast broadcasting radio. "Hey, Zop, check out the talking meat. Can you believe this stuff? They look like trouble. The simplest and least risky answer to protect you system is to nip it at the bud; "nuke the troublesome species from orbit, it's the only way to be sure." Or maybe nudge a few planet killers from the asteroid belt. And (your) life goes on.

Extending your other premise, that wholesale gene-scrubbing might be required, you may be living under a version of Brave New World and have a rigidly self-controlled caste society. Or look at Dune - technology limited by a ruling aristocracy that manage regions rather than nationalstic systems per-se. Look at Imperial China - rulers limited technology for centuries to folter out disruptive developments.

I suspect that any civilization that has established itself, is going to take a no-nonsense approach to newbs. Whether it's (The Day the Earth Stood Still) robots or some UP (United Planets?) we may get a (big)nuke strapped to our planet with the warning that if we screw around we're toast.