"When did a very large percentage of Portland area drivers become entitled to the point that they feel traffic laws don't apply to them?"

Roughly around when cars were invented.

We get a lot of the other flavor of entitled as well. Oh you're not comfortable with narrow lanes? By all means, straddle both going 10 under. Hold everyone hostage at a stop sign because you can only merge if there's 11 car lengths worth of space. Stop at every block because you're lost instead of just pulling over. Left lane hog and ignore everyone passing you on the right. You're the most important person on the road, damnit!