Please - use your brain.

In my ongoing theme of intolerance of idiot drivers, it seems to me that less and less people are able to use their brains nowadays. This was illustrated again today on the way to lunch. The situation is a little unique - the intersection in question has two left turn lanes. About half way along, there's a street on the left. People want to turn out of that street into the turn lanes so they invariably sit there for ages, waiting to cross traffic and try to force their way in to the lanes that are full of traffic waiting to turn.
The solution is so brilliantly elegant that it illustrates just how stupid some drivers are. If they turned right out of that road and then did a legal U-turn, they could simply join the line of traffic waiting to turn.
But no.
Today, the incredibly short woman in the ridiculously large SUV decided it was in fact better to block the entire road, than it was to use her brain. When she eventually did push in to the traffic, she had to cross a slightly raised kerb and a painted double yellow line to do so, thus not only demonstrating her stupidity, but her complete lack of understanding of road signs and traffic markings.
Why?
Why do people have such a hard time using their brain? I just don't understand it. Are people really evolving to be so idiotically stupid that they can't perform the most simple tasks of reasoning and elemental problem-solving? Or is it just plain selfishness?