I assume assume all other drivers are drunk / sleeping / texting / etc. I'm very alert when I do anything conflicting with the "default" behavior other drivers. My suspicion of drivers goes up about 10X when I'm riding a bicycle on roads.
Point being: We've got a bike path here that crosses a fairly busy state route at the edge of a town. Drivers coming into town don't slow down (even though the speed limit changes way back at the city limits and well before the bike path crossing).
When I'm waiting to cross, invariably, some "do gooder" driver coming into town will stop and motion me on. Meanwhile some driver behind them, not expecting someone to be stopped in the road (and going too fast), ends up braking hard to get stopped. I'm not going to put myself in front of that.
The "do gooder" usually doesn't want to "take no for an answer", either, so I end up having to sit for much longer than if they'd just done the correct thing. In some cases I've even gotten exasperated gestures from drivers, apparently miffed that I didn't take advantage of their "charity".
(I'm actually surprised at the amount of squealing tires I've heard, given that anti-lock brakes are on virtually every car on the road.)