There is nothing terribly unusual about these cars in U.S. rail history. They are no more than the lightweight streamlined evolution from the old open platform heavyweight observation cars. I think most people have seen shots of politicans, musicians, etc perfroming from the special rear platform of a train. Those were the original, heavyweight observation cars. But, yes, some of those were business cars or private cars. But some were not.
When streamlining began in the late 30's they changed to this design for observation cars.
In the pre-Amtrak years there were many types of lounge cars(which is what these are).Some at the end of the train, some without the rear taper in the middle of the train,longer busier trains might have a lounge in the middle and in at the rear both. Some trains had, maybe a half coach half lounge in the middle of the train and a half sleeper half observation lounge at the rear. The combinations were endless.
There were observation cas with blunt ends, but with windows. This made it more logical to operate such a lounge in the middle of the train or at the rear either.
And,yes, that rear door could open though I do not know how user friendly it was. If I had a nickel for every time I saw the Royal Palm and the Dixie Flagler back into the stations in Chattanooga with the brakeman standing in the open door of the observation car I would have retired years before now.
And, yes, Amtrak did start out with some observation cars at the beginning. Many obviously became private cars later but Amtrak did handle them in regular service for awhile.
Sometimes there were separate lounges for sleeping car passengers(whether it was an observation or not,)
Keep in mind that there was no national company to set standards before Amtrak, railroads could do and did do anything they wanted to with all kinds of operations of lounge cars,diners, diner-lounges, coach lounges, observation lounges, lounge domes, the combinations were endless. To this day you can go to Tennessee Valley Railroad Musuem and see a coach observation car, blunt ended. It is a heavyweight car modernized to look streamlined for a long gone train called the City of Memphis.I will, in fact, be looking at it tomorrow.
The railroads found the biggest problem with a tapered rear observation car is having to switch it in and out every time cars had to be subtracted or added. Quite a few trains in the pre-Amtrak day started life with a rear observation car but it became too much trouble to switch it in an out.
It would be really hard to try to estimate what percentage of trains in the preAmtrak era had observation cars. Of course fewer would have them as the years went by and they were found to be so much extra trouble with the switching. Maybe 15% of the trains had them. They were almost entirely on streamlined trains which begets the question what percentge of trains were streamlined in the streamlined era and that would be really hard to answer, even with an Officlal Guide in your hands.
I note that these days some people refer to sightseer lounges as observation cars. I would say that is historically incorrect but words tend to change their meaning through the years and that might be what is happening here. There has sometimes been a tendency to refer to domes as observation cars, same thing.Of course what the Canadian (and former CZ) has on the rear is both an observation car and a dome car. One can "observe" more from a dome or a sightseer lounge but the observation car was invented first so it got first honors at a name for itself.
