Although there’s a possible sample bias here (employees whose needs aren’t satisfied will keep looking for other opportunities and leave if they find them)

I think the result is entirely explained by this bias, and the fact that many people take administrative jobs like that right out of college simply because they can't find other jobs.

Specific examples of people exploring opportunities and using their career capital in creative ways. For example, the book mentions a marketing executive, Joe Duffy, who wanted to work creativity into his working life–but instead of quitting and trying to make a living as an artist, he build skills and a reputation in brand icons and logos, until he was offered a job at a company that gave him the creative freedom he wanted.

This anecdote is extremely unusual, for this to happen Joe had to become famous enough that his ideal job was simply offered to him. This is very unlikely for the average person in a job they find boring. They would do better trying to somehow alter their job to become more interesting. This is similar to your later complaint that there weren't any jobs mentioned positively in your reference class of nursing.