Initial approach fix
 

I know some countries have "IAF" written on the approach plate, but I also see a lot of countries that does not have it identified directly on the plate, which ICAO recommends in Annex 4...

Is there something here that is eluding me (they have approaches without IAF's), or is it simply because it it obvious where it is (starts at a beacon usually from the MSA, or holding altitude if that is lower).

At approaches where there are several, GNSS approaches, it's always marked though.

As a general rule, in the US, approaches that require radar don’t have an IAF. I’ll defer to aterpster though. I believe he works with procedure design.

Nope, I am a long-retired airline pilot who was ALPA's instrument procedures committee person most of my airline career, and well beyond as a consultant.

"IAF" has to be charted in the U.S. by FAA charting specs. It should be charted in PANS-OPs countries....but. In some countries where the IAF is also an airway fix, they won't designate the fix as the IAF.