Summary of incident being argued

An observer captures an incident at an intersection on their dashcam. The intersection has two left-turn lanes: the inner lane is left turn only, the outer is optionally left turn or go straight. A box truck is in the outer left turn lane, a white pickup is in the inner left turn lane.

As they turn left, they have a "meeting".

Additional observations about the accident: (1) the box truck cut the corner and encroached on the inner turn lane (2) the white pickup stayed within his lane, but had his right turn signal on (either unwittingly or with the intention to go straight).

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So of course, what does /r/dashcams think? Let's find out

Most of the argument was amicable,
but others not quite as much,
and some even less yet.

And of course, inauguration memes (and context from /r/nottheonion.)

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The video of the incident is in the original post. So who's at fault? You decide.