when using the new wxwidgets driver, (not with the old) although the size of the window and of the box is the same, the size of the hershey characters are approx 1.8 times those of the fonts.
How to reproduce:
examples/c++/x29 -drvopt "hrshsym=1,text=0" (select 7, wxwidgets) -> big hershey characters
examples/c++/x29 -drvopt "hrshsym=1,text=1" (select 7, wxwidgets) -> small fonts labelling
It seems generally admitted that plplot produces consistent plots between all drivers.
Actually the size reported by plgchr() seem wrong also.

copy of seemingly unmaintained https://sourceforge.net/p/plplot/bugs/201/