Everyone is armed all the time and that’s normal, but to draw a weapon is an overt hostile act. A standoff therefore is a game of chicken because both want to kill each other and you want to draw first to have the highest chance of surviving, but even a bandit will hesitate to add a felony murder charge to their rap sheet. The whole town serves as witness when there is a pair of eyes behind every shuttered window. The hero always draws second, both demonstrating his superior skill and speed by defeating the opponent even at a disadvantage, and getting away with murder scot-free.
You’re overthrowing it. They’re both just trying to shoot the other guy first.