In particular, they raised concerns about canvassers’ submitting an inordinate amount of suspect data. That data, some of which NBC News has reviewed, includes entries submitted far from the home or while canvassers are logged into Wi-Fi networks — telltale signs that a door was not knocked on, sources said. In addition, a video explaining how to “spoof” one’s location while submitting data drew attention in Nevada and Arizona, raising further concerns.
This is another reason why campaigns use volunteers instead of paid contractors, if the canvasser is invested in the election outcome, they aren't going to defraud the campaign.