Wages for cleaning outhouses in 1914

Sorry I couldn't get a better scan of the receipt above. It was among my grandfather's papers, but I have no idea why it was there.

It's a receipt for cleaning the school outhouses in Trevor, Wisconsin, dated December 21, 1914. Three men worked a total of 64 1/2 hours over four days on the job, and were paid twenty cents an hour for their labor, for a grand total of $12.90.

I know things were a lot cheaper back then, and a dollar went much farther, but still . . . $12.90?

Perhaps my grandfather saved it to remind himself and/or his children that things could be worse.