I'm sure this is most likely a string of bad RNG, but I'm currently batting at close to 25 raids (of which I'd estimate were 75% Tier 5, 20% Tier 3, and 5% Tier 4... plus maybe a Shinx or two in there, but who's counting?) without seeing a single charge TM. Is anyone here having an experience that echoes mine? We can bond through our shared suffering.
This bad luck comes at an awful time too, as I've been really excited to experiment with second charge moves on a lot of different Pokémon (a number of which have CD or legacy charge moves, which means when I finally do get my hands on some TMs, I'll most likely still be flopping back and forth between undesired attacks before finally getting the second attack I was looking for 5 TMs later.)
Oh well, I'm sure my luck will turn around soon. Hopefully once Niantic realizes that Sinnoh Stones as PVP rewards definitely lose their luster (especially as most of the community has chewed through their Gen 4 evolutions) they'll add Charge TMs to the loot pool; not just because I happen to need them, but because I do think it's smart game-design to be able to play a game-mode and be rewarded with resources that you can invest back into that game-mode.
Anyway, cheers, and hope you're all having better luck than I am!