D&D -- especially 3.x -- has some very wonky definitions of Lawful and specifically Lawful Good.
Lawful is somehow the worst described component of the entire disaster of the alignment descriptions: a fetid pile of ideas that don't necessarily go together: civilization, honesty, honor, law-abiding, ordered, regular, blah, blah blah.
Then the examples of Lawful entities is worse: literal robot men who fight the concepts of change and freedom with extreme, unrelenting brutality.
Then-then the iconic Paladin is straight up a psychopath, described as 'fighting evil without mercy' and the Paladin code paints a picture of a very unpleasant person who can't work with your standard home invaders with a mandate D&D party who can't step out of line even once or the DM is carefully instructed to punish them.
All in all, it's a miracle that ANY reasonable Paladins got played, because the instructions clearly tell you to play one of the worst kinds of people: a holier than thou hypocrite who murders when they don't get their way for fear of God giving them a spanking for not doing so.