What happened to staying in the right lane except when passing?

Thom Jansen of Warren, Mich., wrote in with a question we thought you might well be able to answer. 

My Father was a Truck Driver and an avid reader of Overdrive for most of his life, and as anyone who has a truck driver for a dad knows, my driving habits were constantly scrutinized when we were in the car together.

Which brings me to my question. My Dad would always preach about staying right, except when passing. Why is it that the current breed of truckers does not abide by that credo? Has something changed, or are they just not as “professional” as they once were, possibly due to the job market and the influx of individuals that have migrated to truck driving because they couldn’t find anything else.

Very often I see these so-called truckers driving down the middle lane of the highway for miles and miles even though traffic is very light. And during rush hour it’s aggravating to find them clogging up the middle lane, which results in other drivers passing them on both the right and left side. Whenever I see them in the middle lane, I usually think they are not real truck drivers, because I often see the real truck drivers staying to the right, except when passing.

 How about it, drivers?