Actually, they do. This article is old, but I doubt statistics have fundamentally changed since then. If I'm wrong about that, I'd be happy to admit it, once proven.
https://www.scientificamerican.com/article/howcan-a-poll-of-only-100/
I think the one thing the polling organizations haven't figured out how to compensate for, is people just flat out lying. We saw in the last two presidential elections that the polls were way off, because people liked Trump, but didn't want to admit it to a stranger on the phone due to the social stigma the media placed on people who supported Trump. That was more the case in 2016 than 2020, but it was clearly a real thing.