Is There a Intuition for the Source of the Collusion?

In repeated auctions, the equilibria are very many. There's a lot of possible equilibrium of these auctions. And a lot of these equilibra are collusive. In some way, in order to avoid these things happening, maybe hiding information from the bidders is a good choice. This might explain why, for example, we don't see as back like the identity of the winner or how much they bid. We only see sort of this minimum bit to win, which is completely anonymized. It becomes very hard to coordinate on some colusie strategy when we don't know how many people are in the auction.