That’s odd that you’ve never met a Junior. Not even one? For some reason it’s not a popular custom in Australia? It’s definitely not a custom in Jewish families.
I know many with a suffix. Whether it’s on their birth certificate, I have no idea, but it’s on at least one of their passports. I’ve knowns Jr, II (named after a grandfather), III, IV and V’s. One V was called Quint because of his V.
It's not odd if you've never met one. Why are you still harping on it?