Even if I agree with using expressway=yes to cover both standards, what would be the answer when I ask to distinguish between them as a subclass of expressway ? If expressway=val1 vs expressway=val2 is to be used. it can simply be replaced by key2= =yes / val0 (unspecified replacing expressway=yes ). =val1 , =val2 in the first place.
The argument against to such a common yet vague word can be compared to using soccer not football , and sidewalk not pavement , for the British English criteria. The difference is that a better non-uncommon word isn’t found yet, but other methods of expressing this can be sought.
I don’t understand how access_control doesn’t work in Poland from the summary by @pavvv yet. Anecdotally, the Wikipedia article is titled as limited-access, with “expressway” listed as a synonym only. Doesn’t that suggest access_control= would have a similar level of acceptance in reality?
Alternatively, it could be eg high_speed_road= or something, or even highspeed= following railway=rail directly. That’s the literal translation in many languages too. The issue to be considered is there can be “low speed” “expressways”, and it can have a special technical definition officially (eg 80km/h) for the purpose of construction works at roads. For the former, again unlike the reporting of Poland’s community, there can be 50km/h to even 40km/h grade-separated roads, which may further relate to urban vs rural differences.
In this regard, is expressway=yes supposed to be used differently between urban and rural. on top of international differences? If yes, that would add to its variation. To be fair, this can indeed still show they are more used, and potential (ignoring congestion) higher travel speeds relatively and locally.