To get a poll representative of a population, you need an SRS -- simple random sample. The people you poll are chosen completely at random from an unbiased list.

That's incredibly difficult to do when the person chosen can decline. And as far as getting an unbiased list, good luck. Landlines are lol. Texting doesn't work either.

I think when everyone had landlines it was probably less biased. But with the state of technology today and the country becoming more diverse? It might be falling apart. They need a new methodology.