Why Does Convergence Not Always Mean the Futures Price Exactly Equals the Spot Price?

Convergence does not always mean exact equality due to minor factors like transaction costs and the residual value of delivery options. Even at the moment of expiration, the cost of physically moving the asset or the final, minimal bid-ask spread prevents the prices from being perfectly identical.

Furthermore, if the futures contract allows for a range of delivery dates or locations, the value of that flexibility prevents exact price matching.