I received bogus DMCA complaints (over Big Buck Bunny, lol, multiple times), and Google stonewalled me when I tried to find out the identity of the complainant so that I could litigate against them.
I expect situations like that contribute to the lack of response, along with the fact that providers often ignore DMCA complaints or put things back up without following the statutory takedown period.
Probably shouldn't drip gasoline on this smoldering dumpster fire, but pretty much anyone at a high political level that testifies "I can't remember" is probably committing perjury, yes. Oh well.