The auto-votes are generally from upvoting services. So the first question is: How many upvoting services exist?
These upvoting services tend to sell curation trails. The bots cast the auto-votes in a sequence. My guess is that the position in the sequence is either dependent on political clout or the amount one pays for the service.
The competition in the auto-vote arena would be a matter of bots controlling a large number of upvotes competing with other bots with a large number of upvotes.
BTW: My voting strategy is to look at posts that are at least six minutes old. I avoid reading posts from authors that get a dozen upvotes at the five minute mark because they are most likely using an autovote service.