"the 'we can always steal it' must be at the back of all negotiations."With all due respect, this is a big and mostly incorrect leap. If intellectual theft happens in Hollywood, it's typically an exception and not, as you're implying, a general rule. It certainly isn't something studio execs keep in the back of their minds as part of the development process. That's outlandish.
Most studios are extremely frightened of litigation over this very topic. So much so, that when I worked at a TV studio buying scripts, I was not even allowed to open any unsolicited material sent my way. If someone sent me a package, and I didn't recognize the return address, I sent it off to legal, to be returned unopened. About 99% of the scripts and ideas I was pitched came about in meetings with agencies and/or producers, who were also bringing the same material to all of my competitors.
The behaviors you're ascribing to studios seem to be occurring at the producer level. There's a high variance of ethical and professional conduct among production companies and producers, in as much as they're not public companies like the big studios and networks are. They don't have a set rulebook. Most of the more established producers are unlikely to steal material, because it's a terrible long-term business strategy (a producer's reputation is his meal ticket). That said, are there some shady folks on the fringes of the business? Yes. Anyone who says otherwise is being willfully naive. But the idea that people at studios actually calculate theft into their buying or development strategies is patently absurd.
"What stops the other studio from farming out the 'high concept' to someone else to write an also ran."
Three things stopped me from doing that, and stopped my peers from doing that:
1) Personal and professional integrity.
2) Relationships and reputation. (Hollywood is an extremely relationship-driven business. As a development executive, I was worth approximately nothing; what made me relevant to my employers was my network of writers, agents, and producers I could bring to bear for projects. Burning any of these people would have been career suicide).
3) Fear of litigation.
In that order.
