Why is British Columbia sales tax being charged on iBooks when BC's own documentation says that electronic books are exempt from sales tax?

I recently bought a book on iBooks and on the invoice realized that provincial sales tax (pst) was charge. As I knew books were pst exempt, I went to look at the government's website to see if they mention electronic books. I found the aptly named "What's taxable and what's not" (http://www2.gov.bc.ca/assets/gov/topic/BED47DA4EBDBA60A5F28622B8B2E1451/uploads/ whats_taxable_whats_not.pdf) and started looking. On the first page, it distinctly says electronic books are exempt.

So, my question is - why are we getting charged tax when our government says that electronic books are tax exempt?