The regulations do not specifically require PFC but instead specify a maximum input harmonic distortion for different power levels and classes. Usually the most economical way to meet the specifications is to use active PFC although sometimes passive PFC is sufficient.
https://en.wikipedia.org/wiki/IEC_61000-3-2#Scope
Incidentally, industrial uses may be charged extra based on their power factor but doing this has been considered impractical for consumers so far. So instead they regulate it on the supply side now. It was not a big deal until switching power supplies became ubiquitous.
Yes, that's pretty much what I said.
I just realized I had not thought about my inverter split air conditioner units which I am pretty certain they would have active PFC.
To get back to the OP subject. Low power units like wall warts can have a wide ranging voltage input because efficiency is not of great concern.
Even laptop PSUs may not have active PFC because of space and weight constraints. My Dell PSU does not even have an inrush limiter and I have blown a few fuses in the UK until I inserted a PTC directly in series in the cable itself.
Cheap PSUs for PCs used to have the voltage doubler switch and now are just for a single voltage and do not have active PFC...
Because if they did the would be:
Higher range PSUs have active PFC which raises the voltage to a set voltage and this is in fact a pre-regulator and therefore admit a higher range of inputs (full-range).
Note also that Triac power controllers for incandescent lighting have some filtering but not what I would consider a lot.