The scroll bar is on the wrong side

I recall when windowing systems first started appearing on computers. There was a lot of variation on where buttons went, what was in menus, which way the apparent light source went, and so on. Remember menu items with names like "!Close"? The ! was to indicate the action would happen without any further intervention. I recall a number of apps had the scrollbar on the left side instead of the right. At the time, I thought the scrollbar on the left side was a great idea since it saved a lot of mouse movement. However, over time, the left scroll bar disappeared in favor of the right scroll bar. I've never figured out why. For example, suppose you have your favorite music play open and expanded full screen. You've got a long list of songs in your playlist, and you only want to pick out a few. You move the mouse to the right edge of the screen, scroll down a little, move the mouse back to the left edge of the screen select a song, and repeat until you have your choices selected. Just think how far your mouse traveled to do all that, and think about how much less it would have moved if the scrollbar were on the left side. With a regular, desktop style mouse, this isn't a big deal, but is sure is if you've got a touch pad, or even worse, one of those rubber eraser thingies in the middle of your keyboard.