Only Fast TM, not Charged TM?

Tier 1-3 raids drop about twice as many Fast TMs as Charged TMs, while Tier 4 raids drop about 30% more Fast TMs than Charged TMs. Only Tier 5 raids drop both at about the same rate.

Source: https://thesilphroad.com/science/raid-reward-odds-april-2018/

They are incredibly rare. I have been saving them since November using only one or two every two weeks or so and maybe 200-300 raids later I am only at 60 CTMs after having tuned some Pokemon today. Compared to my 116 FTMs that I use regularly to free space in my bag and help me check on my HP Starmie collection from last round of research tasks, I find CTMs to be the rarest item to obtain in the game bar none.

I have been luckier than you, getting TMs of both types, fairly often, mostly from 5 star raids. Same with my son, so not just me. Here in Thailand raids are very heavily attended ... we often get 2 or more rounds of 20 trainers for each 5 star and perhaps the number of trainers helps boost the TM payout. It is still random I guess, unless the top performing (by damage) trainers get more TMs ... most here go with the auto select which favors highly resistent Mons thus reducing damage but saving potions. As I always select top DPS I know I am doing more damage than most.

I disagree with the poster who claims that TMs are very rare ... I would say very erratic or even random perhaps. My experience in playing PM since the start is that some accounts get lucky for some rewards / features but not for others. I have always done well with 10k eggs while some trainers rarely get them. I am good for TMs but NOT Sinnoh Stones. Who knows why.