Reasons for absenteeism are rarely black and white – you feel unwell so you phone in sick rather than you are unwell so you must be off sick. Even a doctor’s note is pretty easy to obtain as a doctor can only go on what you are saying and reporting. It’s quite rare for a doctor to refuse to give a sick note to someone who says they are unwell.
So really simply, if you are disengaged at work, meaning you don’t care much about it and you might not even like being there much the your “bar” for deciding you are unwell and should be absent is low. If you are engaged at work, love your job and are excited about spending time with your colleagues and working on the projects or jobs that you have then your bar is much higher and you are absent only when absolutely essential.
In 18 years of work I’ve only been off sick for 2 weeks, once with a kidney stone and once with influenza. That’s because I’ve been fortunate to spend the last 18 years working in an environment where I was highly engaged. In the prior 10 years working for a big corporate I was off sick much more often because I didn’t really like the job that much and I wasn’t very engaged.