With the exception of PBS, most of the documentaries on Netflix are dumbed down shows from Ad-supported cable networks. Every time they break for ads, they have to go back and repeat half the information. This is annoying. They just don't have the depth and quality of the PBS and BBC programming.

One hour programs intended to be shown with ads have a 38-44 min. run time. The programs on BBC have a 55-59 minute run time, and those on PBS have a 51-55 minute run time. More material can be covered in the longer run times.

Also, you don't have Advertisers dictating what types of documentaries to produce (e.g. UFO/Alien abduction, psychic, ghosts, political, etc.) Apparently programming with borderline non-truths attract more viewers who spend money on the advertisers products than real factual programming.