When you attempt to bake insecticides into a plant destined for human and animal consumption, the question is pretty damned valid.
Only to someone whose entire knowledge of the subject is "insecticide", rather than BT-produced Cry proteins, which we know an awful lot about, such as how insects react to them (explodes their alkaline guts, which is why they're used) and how humans react to them (which is to say, not at all, since the proteins are digested in mammalian acidic guts that both renders them inactive and lacks the appropriate receptors for them to bind to, causing the insect explosion).
Seriously, there are people who actually know this stuff. No one is just making this shit up willy-nilly.
They say people won't buy GMO-labeled food when what they mean is people won't buy GMO-labeled food at the same price as already-familiar food.
No, what they mean is that people won't buy GMO-labeled food in the face of the anti-GMO FUD machine of propaganda and lies perpetrated by the organic food industry telling people that GMO foods cause cancer and a hundred other diseases despite evidence to the contrary. Also, the cost of massive changes in labeling and packaging to accommodate that kind of labeling mandate will probably cause the price of food to go up by a not insignificant amount. It's not as easy as just slapping a sticker on something that says "may contain GMOs".
At least in the US, there's an underlying sentiment of anti-intellectualism and "my opinion is just as valid as your knowledge", and a lot of people who just straight out don't trust scientists because of their own self-ignorance. This is why we have things spreading like creationism, anti-GMO activity, climate change debate, etc. If it were that easy, these things wouldn't exist. You can lead a horse to water....
"Is the decision determined by the inputs alone, or does the person making the decision change the outcome?"
If you count the internal feedback loops of the neuronal wiring (generated through previous experiences) also as "inputs" to the final decision making process (which I feel is justified), then the answer to both halves of the question would be "yes". No two humans will do the same thing because no two humans have exactly the same subjective experiences that shape their neural topography.
"Are peoples' actions determined purely by physical processes, or is there something ineffable that has to be considered to explain how people behave?"
Just because we lack the ability to sufficiently track and understand the underlying physical wiring due to the massive complexity that it creates doesn't mean that those physical processes aren't sufficient to answer the question. I think the question IS answerable, theoretically if not currently in practice.
Their customers are farmers. Not you. Monsanto doesn't sell corn to supermarkets. They sell seeds to farmers. There would be no fear if not for the organic industry's obviously successful anti-GMO propaganda smear campaign.
For a better idea of how and why this works, this video provides a pretty good explanation.
What would stop a company like Monsanto that sues companies for geting their seed stock contaminated with GMs from suing you for not having paid a license because that jellyfish gene in that GMO Cheeto you ate migrated into your DNA and has shown up on a recent blood test?
99% of all species that ever lived are extinct and that ours is in the tail end of average life expectancy.
99.99999...% of all species that ever lived have never built a skyscraper either.