[throwaway0a5e]

Yeah, it should probably be a blinking red arrow in order to be consistent. I'm sure some committee decided that wasn't different enough from normal red arrow

[lttlrck]

isn't flashing red a fail-safe triggered when the light controls fail that should be treated as a stop sign?

In practice that might work, but it's also a conflicting signal.

[sokoloff]

Blinking red would be a stop and proceed when safe sign. There’s no reason for each car to stop for a lot of these unprotected left turns.