You can't vote on a poll using a 3rd party app. For example, if you click on a poll using Apollo, it opens the Reddit website as a new window and you have to log in again and vote through that website.
This level of friction means I've never voted in a Reddit poll unless I was on a computer, and many other 3rd party app users probably act similarly.
Isn’t polling one of the features that Reddit doesn’t provide an API for? I think that would skew poll results heavily. I know Apollo can’t do polls and it’s one of the reasons I never partake in them on Reddit.