Why does anger become so bad that it results in road rage? Because we suppress it and shame it, until it has no choice but to surface destructively. And then rather than try to understand the anger, we just double down on suppressing it more, which leads to ever increasing levels of explosive anger

You don't think road rage can be the a manifestation of suppressed anger from other parts of ones life?

I think road rage is a prime example of what OP mentioned: anger bottling up because it repeatedly wasn't expressed and then it shoots out like a hose, 100% of the anger being directed at someone who maybe contributed 2% to the person's underlying anger.

I would say exactly the opposite, road rage is a classic example of what the parent comment means. Bottling up anger as if it's somehow wrong to feel angry or express it is exactly how you get to people blowing up in a colossal manner once the lid goes off. Road rage happens when someone overreacts to a small transgression which is exactly what you get with bottled up rage.