Time can in fact be exchanged. For example, jail -- some action is traded for a timeout from society. Also, learning is a time-based process to replace entropy with reason, increasing resources from scarcity.
We do not "trade" time in jail between society and an individual. We deny certain freedoms for a period of time. There is no economic equivalent when it comes to time.
Learning is a process that consumes time now for improved capability or efficiency in the future.