EBay will assess and remit sales taxes for most US states, for European Union VAT, for UK VAT and for Australian GST.
As of July 1st, eBay is also assessing and remitting GST/HST/PST/QST for sales to Canadian buyers.
These taxes are paid by the buyer, not the seller.
However, when we are charged eBay fees for payment processing, the sales tax which is part of the buyer's payment, is also part of the fee.
and the huge cost of global shipping program
The GSP is a US and UK Seller Protection program that is not available to Canadian sellers.
The import fees are made up of duty and sales taxes on the import plus a small (~$5USD) service fee.