As I play alone on Simutrans, (primarily as public service) I notice that certain buildings are only available for random rotation and 0 rotation, others for random, 0 and 1 rotation and some with complete rotation available. I must ask, why? ??? ??? ??? ??
The builder of the pakset you are playing with can provide from 1 up to 4 rotations of a building. Some of them choose to draw all 4 rotations (plus snow variants, in total 8), some of them just 1. You can imagine that it is more work to draw 8 than to draw 1. On the other hand, more rotations makes the pak more beautiful.
It depends on the pakset and whether images for each rotation have been included. For those paksets drawn pixel by pixel making images for each rotation is very time consuming. For rendered paksets it's a lot simpler so typically all buildings have complete rotations.
Rotation is also a relatively new feature, so many pak sets simply don't have other rotations because there was no such thing when they were made.
Pak128.Britain has all rotations for more or less all buildings, I think.
Some which look similar from 2 or 4 angles only have 1 or 2 rotations.
A lot of the pakset buildings have only 2 rotations which is really just a mirror image of a single image. Some of the more recent buildings have all 4 rotations (or 8, for certain building styles). As mentioned, it's a huge amount of work to draw just a single building... adding 3 rotations to that, done by hand, is an even huger effort (and then if you later need to make a change to the image, you can need to make that change on all 4 rotations again... ugh!). And that's just for one building. Using rendered images is much easier as you can do all 4 rotations in one shot.
The cosmetic limitations aside, map rotation's big benefit is in being able to view your network from different directions.