Siure but that doesn't say much about PR, all those flora and fauna can also be found in adjacent countries, should be someone or something distinct about the nation/history.
Just a long standing tradition, there are lots of other people who I'd like to see on the bill, such as Louis Riel, but it really doesn't matter. Ask me what I remember/learned about EU after several visits by way of its currency, nada. With electronic payments happening for a majority of transactions in most places we just don't come into contact with bills as much as we used to.