With millions of voters, the chance that you are correlated to thousands of them is much better.
It seems to me there are also millions of potential acausal trade partners in non-voting contexts, e.g. in the context of whether to spend most of your effort egoistically or altruistically and toward which cause, whether to obey the law, etc. The only special feature of voting that I can see is it gives you a share in years’ worth of policy at the cost of only a much smaller amount of your time, making it potentially unusually efficient for altruists.
It seems to me there are also millions of potential acausal trade partners in non-voting contexts, e.g. in the context of whether to spend most of your effort egoistically or altruistically and toward which cause, whether to obey the law, etc. The only special feature of voting that I can see is it gives you a share in years’ worth of policy at the cost of only a much smaller amount of your time, making it potentially unusually efficient for altruists.