Also, a DMCA claim has (in theory at least) some recourse for filing false claims. Google's ContentID system however doesn't, at least not in any material sense

Also, a DMCA claim has (in theory at least) some recourse for filing false claims. Google's ContentID system however doesn't, at least not in any material sense, so why not file false claims? There is no legal repercussions, and the damage which can be done to your competition is well worth the minor bad press