On the opposite, software development is broad in amount and scope given to one person. That leaves many important decisions to be taken, many of which are slow or dead ends.
My Monday's afternoon: Read hacker news all day and eat ice cream. Thinking about what to poc next (of course, that counts as work).
Coworker Monday's afternoon: Tried to migrate a thing in place to get the new improvements. Didn't make a backup. The update failed and fucked the system. Stayed until 8pm to un fuck it. (Then we'll have to continue restoring it fully tomorrow).
See. He's worked full time and overtime already + many hours lost (for both of us) because we had to fix shit in emergency + many hours lost by other people who are impacted.
That's a ton of overwork and negative productivity. I could eat ice cream for half the week and still be significantly more productive than that.
P.S. This example is for toying around with production systems, it's easy to understand and evaluate. We can do examples with bad design decisions that destroy the project and are 100 times worse :D