[snowwrestler]

The key here is a federal law which outlaws the use of automated dialers to dial mobile phone numbers.

That means that any polling firm that wants to poll people via their mobile phones needs to employ a bunch of humans to laboriously dial every single candidate number--and get hung up on repeatedly. This makes polling mobile phones much more expensive than polling landlines, where you can use a computer to try numbers until someone agrees to take the poll. So most folks will not bother, or will only do very small mobile polls, occasionally.

This was a significant factor in a bunch of Republicans getting a nasty surprise on election night 2012. They simply underestimated how many people without landlines would turn out to vote against them.