Most orchestras have a librarian whose job includes distributing parts to musicians. The conductor rarely dictates bowings; many conductors are not string players, and it's generally considered inappropriate for conductors to dictate technical details for instruments they don't play.

In some orchestras, the librarian sends the string parts to section leaders in advance, the section leaders prepare a preliminary version of the bowings (usually the concertmaster goes first so that other string section leaders match the first violin bowings where appropriate) and return it to the librarian, and then the librarian distributes parts with the preliminary bowings. In other orchestras, the parts are distributed to everyone, and the string section leaders pencil in preliminary bowings and email the section a scan of the bowed part. These are not final bowings for the concert because the bowings may change during rehearsals. Notation software and DAWs are not used here because, again, the bowings may change during rehearsals and should not look like they are printed.

It would be absolutely impossible to mark a part prior to rehearsals so that individual orchestra members do not need to mark anything. The main reason is that too much may change during rehearsals. Even if the bowings do not change, musicians still pencil in things like where they need to pay especially close attention to the conductor (drawing a pair of eyeglasses is typical), cues from other parts that they should listen for, indications of when the conductor is subdividing beats or what conductor cues mean, etc. In addition, sometimes musicians may write in fingerings for difficult passages, and those can't be standardized because everyone's hands are different.

Most orchestral musicians do not look at the whole score when they practice, and most orchestras I've played in do not distribute the score in any form. (My current orchestra does routinely distribute the full score, but it's the only one I've played in that does.) Sometimes the section leaders also mark important entrances in other parts that should be listened for, alongside their preliminary bowings; musicians often also pencil those in during rehearsals as they notice useful reference points in other parts. I do like to review the score if possible, as it helps me know what to listen for. But I usually wait until the first rehearsal to pencil in cues, because usually it takes at least one play-through to understand when a cue is helpful and when it would just clutter up the page.

In my current orchestra, the librarian sends out a Dropbox folder containing the full score and all the parts 1-2 weeks before the first rehearsal. String parts are normally not marked at that time. Bowed string parts are posted in the same folder shortly before the first rehearsal, but unmarked parts remain available; most of us print the unbowed part and pencil in bowings from the bowed part. (People who use tablets do the equivalent, because it's important for markings to be erasable.) Section leaders usually email the section a scan of their current marked part about halfway through the rehearsal cycle so that everyone is up-to-date on any changes.