eBay Canada is a 100% foreign owned company, forget where it is registered, and Paypal I believe is registered in Luxembourg or Switzerland, I forget which, but that doesn't qualify eBay to not comply with Canadian law. If they choose not to surrender the documents, their doors will be padlocked and bench warrants issued to the management of eBay Canada for contempt which would likely result in a high profile "perp walk".
Really makes no difference, Revenue Canada operates on the principal that you are guilty until you can prove otherwise and no company has ever prevented Revenue Canada form securing whatever documentation it's little heart desires 😛
There are 2 basic issues, Revenue Canada wishes to get the income tax it is owed by eBay businesses that seem to think they don't have to comply with the tax code because they are selling on the internet, so anyone that is a "Power Seller" has been classified by Revenue Canada as a "Business" and the appropriate tax returns and remittences will have to be made at some point in the near future.
The second issue is the collection of GST from these businesses, many of which seem to think they don't need to comply with those regulations either, so they will be doing a lot of whining when they get the invoice from Revenue Canada for 5% of their sales for the past 5 years. Revenue Canada will of course refund the GST on shipments made out of the country, just as soon as one proves what portion of those sales were exported.
The only good news is that while there is no statute of limitation on tax evasion, typicaly Revenue Canada deals with the immediately preceding 5 years and offers easy payment options spead over 12 months if required to facilitate compliance. The alternative is jail time and they have no quams resorting to such penalties.