I think I see where the confusion is. The Indica "brick weed" that's commonly sold is typically imported from countries where it grows naturally in the wild. The Sativa strains you're referring to tend to be grown in the setting of domestic indoor operations. The Sativa strains are more expensive and are in higher demand and are higher risk due to a) the time that it takes to grow them and b) the fact that it's being done in a high security and low corruption country. This provides motive to grow them as quickly as possible and make them hard hitters when smoked. You want to produce the most "bang for buck" in terms of the physical space you have available, so high concentrations of the most noticeable compound (THC) are favourable. There is also a higher correlation between hardcore drug use and those strong strains, whereas more casual users are likely to buy the Indica brick weed. All of those documentaries are probably referring to the hardcore users, not casual users. They are addressing a real concern but gloss over the fact that the reality is more complicated than it appears on the surface.
