We always want to avoid wasting time. We fear that once we spend our time on the wrong things, it's gone forever. But what if we can recover spent time?
The lives of the greatest geniuses corroborate your assertions, even (or especially) that you could apply some aspects of the cartoon Avatar in a constructive way. Isaac Newton, James Clark Maxwell, Claude Shannon were all restless tinkerers whose “hobbies” somehow fueled their profound insights.
I do think you’re being too generous to underemployed road workers. I think what you’re really seeing is theft in plain sight: no bid, fixed cost infrastructure projects given to politicians’ friends and funded by taxpayers. It’s one of the oldest and most pervasive large scale scams. Everybody sees it, and nobody understands what they’re seeing.