Cyril, here is one possible answer:
As a bass player, when one is playing in the extreme upper register, one simply doesn't have the same flexibility. That will be less an issue on a cello, and even less on a viola or violin.
But, a couple things will be common to all: as the length of the vibrating string gets shorter, the manner in which it vibrates changes. For the clearest example, take pizz. When played in first position, the note will ring for some time, while when played in an extreme upper register, it will barely ring at all. Also, as one plays further up the fingerboard, string tension increases, considerably so in the extreme ranges as the distance from the point where the string touches the fingerboard (the stopped note) to the fixed bridge height of the string gets much shorter.
Also, true for all strings: as one plays in higher positions, one must move the bow position closer to the bridge as well.
In general, one simply doesn't have as wide a range of options at the top of the fingerboard that one does in basic to moderately high positions. Extreme virtuosity in the highest positions is fairly rare - sometimes required for solo literature, less so for orchestral works.
Again, speaking double-bass (as that is what I am most familiar with) in the VSL world some articulations go up roughly to the octave + a fourth or fifth or so on the top string. A number of the articulations go up to the two octave harmonic, and a couple go a whole step above that.
In the solo literature, a very few pieces require the soloist to go up to the Bb (a minor third above the two octave harmonic). Those notes are generally written very carefully, and prepared for, as they are extremely difficult to play. OTOH, being able to play in moderately high to high thumb position is the norm.
Contrast that with orchestral music, where it wasn't until the turn of the 19th into the 20th century where thumb position was required at all. Similarly, less virtuosity is generally required of second violinists than the first violinists (there are numerous jokes about 2nd violinists and violists compared to 1st violinists, as well as bassists compared to cellists, and bassists in general).
Anyway, those are some general thoughts.