Finding the best possible choice is impossible, but selecting the choice that maximizes expectation is possible. The former would be driving a different route because you know that a specific driver would rear-end you, and is impossible because it requires knowing the future. The latter would be driving a different route because you know that there's an annoying left turn.

The distinction isn't in whether your have access to all possible information for use in a decision. It's whether you use all available information in a decision.