This is a ridiculously deep topic. A lot of it is about understanding the limitations of given instruments. Trumpet shouldn't be written very high for very long and the extreme low register doesn't sound very good. Wind players have to breathe also. Other things just have to do with how instruments sound in a given register. If your only idea of how an instrument sounds is based on a sample, you'll be pretty far off. My wife plays oboe and complains about people writing very high. Yes, she can play those notes, but it's really not the best register for an oboe and it doesn't sound good. If you're writing something in the extreme register for that instrument, you need to know explicitly what you're doing like the bassoon opening to Rite of Spring that is very very high. It creates a great effect, but the bassoon looses a lot of its character up there.

People without a lot of actual background listening to these instruments in real life and working with musicians that play them don't always quite understand.

There are also plenty of physical limitations. There are trills that are impossible to play on a flute or example (not that John Mackey gives a shit). Sure, you can write it and a flute player can play both notes, but due to the mechanics of playing the instrument, it would be impossible to do without two people.

Mechanical and physical limitations have to be considered. You also can't always write ridiculously large chords for piano and there are some things that are difficult to do regardless of the size of the hands of the player.

For mechanical reasons, if you were writing a tight chord for two violins, you wouldn't have one violin on the top two notes and the other on the bottom two. You'd stagger the notes between them so that the interval is larger for each of them.

That's a physical thing to consider, but there are also general rules about scoring different instruments and instrument families together. There are lots of those out there.

Then there are issues of dynamics and the limitations of those in given registers for certain instruments. It's going to be very hard for some sax players or oboe to play very delicately very low. It's going to be difficult for trumpet players to play delicately very high.

Then there's issue of limitations of instruments. While most flutes will have a B foot, not every bass clarinet can be expected to have a low C extension.

The minute details of orchestration for different instruments could fill a book... which is why they have... many times over.