Look at it this way. When the US wants to prosecute a suspect in federal court, where do they generally hold the trials? In the whitest, most affluent part of Virginia. So the jury, while random, is still taken from a specific pool of people who lean a certain way politically.
If you think polling data isn't politically motivated and influenced by sample location, age, and the way the questions are formulated, you're deceiving yourself. What's that saying? There are small lies, big lies, and statistics.