Why is that so?

There is something about planes and trains that keeps puzzling me, and almost every time I am on one or the other, I think of writing about it.

Today, I finally sit down to do so, and I can not help but wonder if other people have noticed and wondered about the same thing:
the distance at which the seats on trains and planes are placed in correspondence - or, rather not corresponding - to the windows.

How many times have I booked a window seat on a train, only to find myself sat right next to a stretch of plain wall, having to crane my neck or sit rather uncomfortably, leaning forward, if I wanted to see something else than the pages of my book or magazine?
The same happens often enough when I am on a plane; I ask for a window seat (or book one when I use self-check-in) and end up not knowing whether to lean way back or forward in order to have a view of the outside.

And it happened just the other day, when, a week before Easter, I travelled to England to see the family:

I took this picture from my seat on the plane, determined to finally write this blog entry, and you can clearly see that my normal field of vision would have been with the wall right there in the middle of my seat space instead of a window.

Now, why is that so?
Who plans these things in a way that they do NOT correspond?

Of course I know that many different companies deliver the various parts of a machine as complex as a train or a plane, and I am quite sure that whoever designs the hull and determins where the windows are going to be is higher up in the production line than the companies who deliver and mount the seats.

But why can't those people who design the interior not do their layout according to the blueprints of the hull, which I am certain they can get hold of if they need to?
Why can't they say, for instance, "Right, these windows are spaced at an interval of xx.xx cm (or inches) from each other, so let's place the seats at a corresponding interval, making it one seat per window" ?

It should be simple enough, a naive person like me thinks.
When I have a dining room or a study to furnish, I will make sure that the dining table or desk is placed at just the right distance to the window, and when someone decides to hang curtains, they usually take a tape measure to have the right length and width of each curtain fitting each window, don't they?

So why does a similar principle not apply to trains and planes?

Right now, I don't know the answer, and I have no idea whether I will ever find out.
But most of the time, in the end I do get to see something from where I am sat on that train or that plane - as I did last time, when we left the airport in Stuttgart and I was able to take this picture: