Interesting site Aidan, thanks for sharing.
"
they talk about how the banknotes did not circulate but circulated between banks"
-the same can be said for many early Dominion banknotes in higher denominations (such 1901 P-25A
$1000 or P-25B
$5000). In fact Dominion of Canada P-7/P-7A (1866) & P-14/P-15 were likely intended exclusively to be for bank/business transactions (& not general populace) since these were vast sums of money in back in those days. This DOC practice continues with 1911 (P28/P29); 1917/18 (P-32A $5000 ;P-32B $50,000) 1923/24 (P-34ABC $1000, $5000 & $50,000 notes) & 1924/25 (P-36/P-37 $500 & $1000). Most of these exist in specimen or institutions only.
Although the BOC issued all of its banknotes to public and private banks it is more likely that the $500 & $1000 (P-54 to P-57) were used mostly by banks or businesses for business transactions. It is one of the reasons it is so tough to find the $500 (& the $1000) have such high book values today.
Fun fact, only about 10% - 15% of todays worlds transactions actually use cash (banknotes). The majority of transactions are electronic.