It's collaborative to the extent that the playwright (or producer) has hired the director to tell their story. In order for the director to get the job, he had to have a specific concept of how that story would be told. The playwright and/or producer liked that concept and got the job. Actors are rarely told exactly what that concept is because the director wants to massage the actors performance so that it's organic and intuitive, and not result-oriented: but the director is shaping the performance so that it fits into his concept of how to tell this story per the playwright's intent. That's why the actor gets cast. The actor's audition is their understanding of the work and what they create in the audition is inline with the director's concept of the story which is why they got the job.
I respond as both an actor/playwright. Our job, as actors, is to create behavior based on the character's background and the playwright's intent. We exist to tell the story and support it. If the writing's good and the director is talented at both concept and how to work w/actors. This is an harmonious process. If the director is result-oriented w/out a strong creative process or if the actors are subtly trying to re-write the character based on their personal story, then the process goes awry and the production suffers. I have had amazing experiences as an actor and a playwright when the process works, but I've also had times when it didn't and that feels crappy. Now I don't accept any theatre gigs without having read the script, have a full cast list and director and playwright attached. They don't pay us enough to work with folks who don't honor the process.
So what do you do when you're in a crappy process?
Don't hate me, but here's what i've learned: In theatre, unless it's broadway, a director/playwright you're dying to work with, a role that is sexy, juicy, splashy and exciting to play and will move your career forward because it's a great part (which will inevitably lead to at least a few amazing reviews), Quit. Period. End of conversation. And don't look back. I've done it and the same theatre hired me a couple years later and treated me well, because they knew I'd walk.
It is the only way to work in NYC for a penny an hour and still love the craft. And then target directors/playwrights you want to work with and follow their work like a demon. Show up at readings and openings and share your thoughts about the play and let them know you're a fan and want to work with them. I've done that with some famous directors and playwrights and they call me in all the time and when I invite them to shows they come. Its just a matter of time. And everyone else, I simply do not entertain offers from folks I'm not mad about working with and scripts that move me deeply and will move my career forward in terms of visibility and letting the industry know that I can do a lot more than they've typed me for. There are creative concerns, but business concerns are paramount in theatre because you're basically working for free, so you have to weigh those decisions carefully or you'll end up starving to death in your career and/or growing despondent. Take care of you and your art first. Then the story and the project are considerations. I learned this from Gloria Foster:
"Gloria Foster, instead of searching for fame by trying to be in many different productions, searched for roles in which she would be able to perform at the best of her ability. She once said, "Young people today, I think, are thinking in terms of stepping stones.…I don't know that I ever thought that way. It sounds ridiculous, but I was always thinking in terms of a more difficult role". She won fame by performing her roles magnificently, not by performing the maximum number of roles that she could." Wiki
This description of the process sounds yucky and corporate
The entertainment industry is absolutely is a corp structure. We seem to forget that or we choose not to deal with it and that's fine. Then you should stop reading the rest of this article. But if you're ready to be a working actor for the life of your career, which means taking the business side head-on, then keep reading. Both paths are viable. It's up to you to chose and find joy in the choice.
And that is why we should be making our own work. Look at who funds arts, look at whose work gets produced the most and what messages keep getting repeated over and over again. No accident at all. Sometimes it gets circumvented if a writer has a huge following for their work, then the corp structure is going to give over to the artistic demands because that writer has proven they can put butts in seats. But again, that's a business decision affected by a business outcome.
The good news is there are millions of ways for us to re-create ourselves (thank god for the internet) and tell the stories you want: it ain't easy. I wear 5 different hats, but it's totally possible. Someone asked me at Sundance was I producing movies so I could get a job at a Hollywood studio: and I said No, I'm producing movies that Hollywood studios won't produce because they are stories I want to see." That means sometimes, I won't be making thousands of dollars, but it does mean, I'm always working on the stories I want to tell and making a living which is ultimately my purpose as an artist and human being.