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.
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.