Reasonable, predictable expectations are necessary for daily life. If you couldn't expect other drivers to generally stay within their lanes when they needed to, you'd never get in your car. And if you didn't actually know whether a ketchup dispenser would squirt out sauce or poison, even Costco's famous hot dog deal would be a bust.
But that doesn't mean life isn't just chock full of the unexpected, and it often shows up with little explanation behind it.