The red screen error isn’t about the color. It’s in reference to the uninformative error screen that often pops up when developing with React Native. The amount of information you get from the error, stacktrace, etc. is not all the dissimilar to seeing a blue screen of death on Windows. It could have been any color and the issue would have been the same.

Visual consistency is important. Users quickly become suspicious when they see visual glitches (think of your car making weird screeching noises while driving).