People enter their vehicle registrations wrongly because they can't tell the difference between 0 and O on their licence plate!
I'd suggest that the vast majority of people know if their registration had a 0 or an O in it. I can remember the full registration of every car I've owned. I've never heard anyone outside of this forum suggest it's an issue. How many people will even go and look at their registration on the front of their car before entering it into a system?
You said in your original post in this thread:
As a result, people frequently enter their licence plates wrong into computer systems (for example, when renewing road tax).
That example is rubbish for a start. When renewing tax, you need to provide both the registration and a document reference number. If the registration is wrong it won't proceed. It's as simple as that. Obviously people will make mistakes when entering number plates into parking systems etc, but those errors would still happen regardless of if 0 and Os weren't used (as I can tell you from experience, when I got a parking pass issued with the last 2 letters transposed!).
I really don't think this is a major issue.