it's possible they're "disposing" of these ballots at the local landfills, ditches etc, and the idea is that certain people are clued in and know where to look for all these intact ballots to collect them for misuse.
unless they're watermarked or otherwise have some sort of traceable markers on them, this would be a way to circumvent surveillance and muddy the waters as far as chain of custody (if it even exists, and it shoudl with ballots) goes