A few thoughts to ponder...
It would be great if we were able to make money every minute of the day, in which case the time/money calculation would be easy. But most people only get paid for time on the job; in situations (e.g., shopping, cleaning the dishes, etc.) where we are getting paid $0/hour and are usually spending $xx/hour, saving a few $$ is cost reduction, not income reduction.
Ditto for commute time...if you spend 30 min commuting to/from a job, shouldn't that time be compensated? Otherwise you are essentially giving up an hour for free.