R9-3, R9-13, R9-14, R9-15, R9-16, R5-2, R8-3, R9-3, R14-5, R9-4

R9-4 has an R9-4a where it's words, and I'd bet you that's because someone argued in court that the former bans giving thumbs up, not holding up a hitchhiking sign.

Do Not Enter has words but that's just extra lettering overlaid on a universal pictogram sign.

there is no "most" in american signs for common/universal things like skateboarding, swimming, smoking, etc. For almost every every "No" sign that exists, there exists a counterpart "slash" sign. Add to that not every "no" sign is a roadway sign (eg no smoking)

There is a legal difference between Parking, Standing, and Idling a vehicle. Not every jusrisdiction has distinct bans for each, so there isn't a universal way to represent each. You also need qualifiers - any time, or certain hours, or either side of the street, so you get those signs with words.

You can't really do a picto for "No commercial vehicles". I suppose we could do a picto for No Thru Traffic. I could also see that you can do "No Pedestrians Bicycles Motor-driven Cycles" with 3 pictograms (IMO more than like 3 words on a road sign is just a bad idea)