Those are some pretty stupid examples. But I've seen just as bad in games and in many of the D&D novels.
In fact, I've seen Salvatore use some pretty infantile alignment-type stuff. Like the book where they're nowhere near civilization, and they find evidence of hill giants heading to the Spine of the World. And Drizz't essentially says that they're evil, so they must kill them.
It's not that group of people would just decide to off a group of wandering hill giants that bothers me. I can think of many reasons that make total sense to do it. It's that Salvatore basically said, "They're evil! We're good! Let's go kill them!"
There's one in Crusade by James Lowder too.
King Azoun and Vangerdahast (or whatever his name is) visit the Kahn's camp. Once he comes back, Azoun's coalition gets the misplaced notion that he fought his way out of the horde's camp and is virtually transformed from a mix of motley units into an army rallying around Azoun. Morale is given an extremely precious boost. Meanwhile, Azoun's daughter and head general have a fit of the Lawful-stupids and counsel Azoun to disabuse the army of their misconception because it's a lie. Other leaders argue that he shouldn't because the army cohesion is too important. At least Azoun agrees with the smart military leaders in this case.