Can Ethereum block builders be trusted to honor their auctions?

Ethereum block builders run auctions for MEV (maximal extractable value) opportunities but have zero incentive to honor results once they see what searchers bid. The researchers modeled what happens when builders defect with some probability and steal a fraction of the winning bid, finding searchers rationally shift to safer bids that deter cheating. Using real Ethereum data, they show sandwich trades are already competitive enough to resist cheating, but naked arbitrage and liquidations expose far more surplus to builder theft—proving auctions need built-in constraints, not just format tweaks.