In movies, when a bomb needs defusing, why do the bad guys always use consistent coloring of wires? “Look for a red wire, cut it.” Would love to see a movie where all the wires are black. “Uh, there’s only black wires. The bombmaker is a sadist.”

It would be an option. But it would also reduce the numbers of bombs who make it intact past the assembly phase. Ditto the number of bomb makers.