Headscratchers / This Is the Police

• What you can and can't send SWAT to seems arbitrary. You can send them after every investigations suspect, no matter the crime, and I think a few calls where there's one perp with a gun who hasn't shot anybody, but not to a call about people handling crates of machine guns, or ever as backup. Is there a logic or Deliberate Values Dissonance thing I'm missing about the use of SWAT? I know they're used more often these days, and the game's time period is ambigous, but aren't guys with machine guns still guys with machine guns?