When driving the car, I tend to work on the assumption that the other driver is a useless idiot until they prove otherwise. For example, I don't turn right across a lane until the other driver has started their turn or they have slowed to the extent that it is the only conceivable option - it doesn't matter if they are indicating or I have looked them in the eyes. The only proof of intent is their actual action. Treat them like assholes and you will only be pleasantly surprised when they show they can actually drive - the bad drivers just confirm your normal assumption.
When on the bike (road or MTB - no motorbike), this becomes especially true irrespective of whatever clothing I am wearing (hi vis etc).
IIRC the military did research about the whole SMIDSY issue as it relates to pilots and it is a definite thing. They actually train pilots to change the way they look as opposed to scanning (which is what most of us do) https://www.cyclingnorthwales.uk/cam...nt-for-safety/