Well yes most people only by singles because they aren't heavy music listeners. Plus most of those people listen to a type of music that the music industry has constantly provided where an album has one or two decent songs and the rest are horrible. One key difference between movies and music though is that heavy users listen to the same album multiple times. Thus, I buy numerous albums every year because I buy music in genres where if the music is good, usually the whole album is good. Most metal and rock bands you either like the entire album or none of it, give or take a few mass-market oriented bands. That is because most metal bands have an artistic vision of some sort and tend to provide cohesive albums. There are a few exceptions where only one song is good but I have decided to buy either the full album or nothing and thus not give any money to bands that can't write good albums.
I also buy tons of movie soundtracks and the occasional classical recording. I've found that quality movie soundtracks, the ones that are worth purchasing, are worth listening to multiple times over the years. Even some soundtracks I bought way back when I first started collecting, I pull out occasionally and listen to completely because the music is that good.
Netflix on the other hand is perfect for movies because the average user, and even in many cases the heavy user will watch a movie once and move on to something else. Those who want to watch a movie multiple times can always go out and buy a DVD or Blu-Ray if they want to own a copy for repeat viewing. Even on netflix streaming there is nothing to prevent someone from watching the same streaming movie multiple times.