Many VFR pilots I have spoken to have difficulty in working out what the correct frequency is when at 8500 in areas where there are different frequencies allocated above and below 8500.
Most if not all the areas you quote are in VNC coverage so if what you claim re VFR pilot difficulties interpreting charts is true, that's a sad indictment of the state of training.
Incidentally, where is it prescribed that ERC's are "IFR" only charts?
For the close on 40 years I've been in this game many VFR pilots have also used ERC Lows (and RNCs before them) both inside and outside visual chart coverage because of all the useful info on them, including tracks, distances & LSALTs between major locations, location of IFR waypoints and HPs etc. i.e. data which just isn't available on visual charts.