The real issue is the change in the phone system. Pollsters used to just dial a random number in the telephone book. Now most numbers are unlisted, and most peo

The real issue is the change in the phone system. Pollsters used to just dial a random number in the telephone book. Now most numbers are unlisted, and most people won't answer the phone to strangers (or the people that do answer are rather unrepresentative, at least.) All polling methods require getting a random sample of the voting population to be accurate. That's super hard, perhaps impossible.