Days? Maybe. Weeks? On average? Nah... But, please, do continue your explanations of "see, this is why Europe can't compete"
But yes, these are averages between 1 person having 12 weeks and 12 people with 1 week. It's most likely power law distributed, so the average will feel weird.
There are people with cancer, severe car crashes and other horrible but temporary medical conditions in this average.
Oh, yeah, I know. One of our top (young! sad!) people in .nl has been intermittently-working for, like, months now due to that, unfortunately. But... that doesn't count as "sick leave"! Because, it's, like entirely foreseeable!
What is happening is that they, through the medical consultancy working for the employer (i.e. "us"), submit their proposed working schedule a few weeks in advance. This will have several 'non-work' days (around chemo), some 'partial-work' days, and so on, basically with hourly granularity.
"We" then plan and account accordingly: "we" pay for a few hours, insurance for a few, national-level insurance for a lot, but all "we" see is a plan for actual working time.
Conflating any of that with "oh, you can just stay home whenever you want" is sick and wrong, like so much of the discussion here around "Europe." I mean, you get eviscerated for wrongly naming a Chicago suburb, but blanket statements about an entire continent are de rigeur
It's difficult to do a back of the napkin calculation, but you can easily see how 16 colds x 3 days / 2 parents leads to 24 excess sick days for parents per kid (discounting for some overlap when multiple kids are sick) over the first few years.
[1] https://github.com/robert-koch-institut/GrippeWeb_Daten_des_...
Okay, let's consider what laws like this (the existing one) do.
In the US most employers don't care if you take a normal number of sick days, don't require a doctor's note, regardless of whether the law allows them to. Sick days are like vacation days, it's your own business how you use them. This is fine. And if you want to make a major long-term disability claim then you'll be expected to prove it, but that seems overall pretty reasonable?
That's the common case. No major incentive for employers to cause friction with workers who are mostly acting in good faith. Then there are employers who are, let's say, less selective about their employees, will hire anyone willing to do the job, but correspondingly then see a high rate of fraud. These employers want to be able to demand evidence all the time because the sort of people they're willing to hire would be taking three months of paid vacation a year as sick days if they could get away with it.
Since the law applies to everyone, what does a law like that do? In the common case it does nothing because the employer doesn't do it regardless. In the high fraud cause it prevents something good and increases actual fraud.
So the only time it does something good is the uncommon edge case on the other side where the employer requires that even though their employees mostly weren't faking sick days. And because most employers for that type of work don't do that, those employers don't get any major benefit from it anyway and employees don't like it, the ones who do are at a competitive disadvantage, so it stays uncommon.
Which means the main effect of the law is to cause problems for the employers willing to do "second chance" hiring of people who might screw them over, which harms not only the employer but also those workers when employers stop being willing to hire them because the law requires them to take the hit if they do.
In .nl (and .pl also, although I'm less familiar with actual practices there, just because we haven't had anyone sick there in the last decade or so) there is no "normal number of sick days", and a "doctor's note" is also entirely unheard of.
If you cannot work for medical reasons, you report this to your employer, which will then (in most cases) hand off things entirely to a medical consultancy working for them. Obviously, this will not be done for 4-to-8-hour absences (again, in most cases), but definitely for anything beyond that, and if an employee tries to game the system, there are safeguards for the company there as well.
The medical consultancy will establish a plan for working hours for the next month or so (depending on the severity of the condition) and submit that to the employer: they don't get any details beyond that (in fact, that would be highly illegal). Depending on the duration of employee absence, there are various levels of insurance that (may) kick in, but the main focus is to provide a (literally) workable schedule.
Oh, and if an employee gets sick while on holiday, the same scheme applies. I found that one really gets everyone nonfamiliar with "European" working culture going...