Hi – it seems like your trivial jobs were actually the important ones. That is, the jobs that if you let them slip bad things will happen. I am pretty sure DHH is referring to things that seem somewhat pointless to the person doing the task/project but for some reason the task/project assigner says they have to happen. Eg a meeting with no fixed agenda or expected outcomes that has to happen because they always happen.
The other angle is on a personal responsibility front, where we find ourselves doing things during the work day that make us feel busy but actually don’t lead to any useful outcome. If we aren’t careful, it’s easy to fill our days with them. I call things that fit into this category green noise; that is, as a salaried worker you can justify why you are getting paid to do it, but it’s likely not that important/urgent and you probably derive some enjoyment – not necessarily satisfaction or true business benefit - out of doing it. Eg even though I work in marketing, do I really need to scan Twitter every 5 minutes, or is it a filler job I’ve made up to procrastinate/shift focus from the real work that needs to be done?