Turn Indicator Colour

Simple Question:
what is the best colour for the turn indicator on vehicles?

I was used to seeing vehicles which had orange coloured lights for turn indicators and red coloured lights for brake light and tail light.

But now I see and get irritated by turn indicators which are ALSO red in colour! Isn't it better not to confuse the driver behind and simply keep the colours separate?

Worse than this is, the concept of using the brake light itself as a turn indicator!!! At least once I almost FAILED to notice that the car in front of me was signaling to turn since in that car, one of the brake lights turns into a flashing light (to indicate the 'turn') while the other remains a solid red.

I am not sure how much research has gone into this GREAT IDEA!!!!!!

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