Early in the first movie (and this counts for both "firsts"), we're introduced to a Jedi mind trick -- a way for Jedi to manipulate others. It's explained to viewers that The Force gives "power over the weak-minded." Apparently, being stupid in the Star Wars universe is a serious enough crime that your free will can be taken from you by some dick wizard.
"You're attracted to older men. You don't need that shirt. You have a latex allergy."
The thing is, there's no real indicator of what the Jedi mean by "weak-minded." It's not just stormtroopers who pulled Tatooine checkpoint duty. Powerful monarchs are apparently susceptible, while mob bosses and junk salesmen are immune. When you think about it, the "good guy" Jedi ability to control minds really seems to work only on the exact minds it shouldn't.
When you think about it more, you realize those incompetent stormtroopers that let Obi-Wan drive through the droid checkpoint were almost certainly killed later by their supervisor. We doubt Darth Vader would have taken, "Some old guy vouched for those robots," as an excuse. And while on the subject, would they even remember? A Jedi mind trick is probably like getting blackout drunk. Later that day, those two stormtroopers were being pulled into the air by their throats and shitting into their plastic armor with absolutely no idea why it was happening. It might have been nicer to just run them over with the landspeeder, Obi-Wan.
"You caused the accident. You don't have insurance. You think the old man will go away if you pay him."