[fencepost]

> Are they tossed because of malicious intent, or because they can't change the outcome of the election?

Highly variable, but I'm pretty sure it's a lot more to do with the laws of the states than with whether there are enough provisional votes to matter. In looking up some things for an earlier comment I saw one mention of persons casting a provisional ballot then having 3 days to bring proof of eligibility to the county Board of Elections and a separate mention (for another state) of the Board of Elections investigating provisional ballots and informing voters if their ballot was discarded instead.

I'd be surprised if anyplace had a law of "you don't have to count them if there aren't enough to change the outcome," but I've been surprised before.