I notice license plates. It’s a curse. Anyway, here in Illinois, zeros look like letter Os. One exception is amateur radio plates if the license callsign has a zero. I can’t find a photo of an IL example online but it’s explicitly a zero with a slash run through it like shown here:
https://www.quora.com/On-a-license-plate-how-can-you-tell-the-difference-between-O-and-zero
It used to be that the number part of a ham callsign was tied to you geography so, for example Illinois, Indiana & Wisconsin would all have a 9 and you’d need a new call if you moved to a different area. However, that was lifted by the FCC some time ago and you can now apply for a vanity call with any valid combination. I’ve considered applying for a zero call (formerly only for CO, IA, KS, MN, NE, MO, ND & SD), mostly because it looks cool and I qualify for a shorter call from my current 6 characters. But I also wondered if it would get me out of a ticket … not that I get many.