Is there a reason the sleeper cars on most long distance trains cannot be assigned a specific directional orientation, barring unforeseen circumstances? Seems like it wouldn't be that hard to figure out which way to build the train. Does Amtrak not have easy access to any turntables, wyes, or half-circle tracks?
I'm not sure that I would say that there is a specific physical reason, although there might be a few places where they couldn't easily wye, but rather I think that it comes down to costs and the fact that it's just a make work thing. It just simply requires too much time and effort to worry about which way the cars face. And that means increased costs too.
Plus every time you cut apart a train, you risk a possible accident. In the winter you risk a freeze up on all the cars; in the summer it could take several hours to cool the cars back down. Also during switching, all other work must stop on the train. All cleaners have to sit down and do nothing. Can't load food onto the train, can't load linen's on. All work stops! That can mean the train isn't ready for departure on time and again, it increases costs to have all those other workers basically twiddling their thumbs instead of working, while that switching is going on.
And frankly on most trains, it really doesn't matter which side your sleeper ends up on. Probably the biggest train where it makes a difference is the Coast Starlight. And even there, if you get the views of the Pacific Ocean, then you're not getting the best views of Mount Shasta.