That's exactly why they are a better choice, like the imaginary bridges on current Euro banknotes.

The selection of people is also quite poor but that's because people are a poor choice: Most notable historical people are very linked to specific countries, often against other countries so picking neutral ones is hard. They also clearly decided to have an equal number of men and women, which makes it even harder. Obviously there aren't enough different banknotes to represent every country, either.