While some Americans seem to fear foreign shipping, there are a couple of practical reasons.
One is USPS' insistence that parcels for foreign destinations be brought to a Post Office and handed in over the counter. Extra work, especially since many sellers can arrange home pickup of parcels.
UPS is a cheap and efficient way of shipping to the Lower 48. However, a US seller used to using UPS will get outrage and horror from Canadian custormers who are charged $25 and up for customs brokerage (plus the duty and sales tax applicable). This kicks in on $20 purchases.
I believe that US sellers are charged an extra fee for accepting foreign PP payments.
And there is the "tarred with the same brush" syndrome. One bad Canadian (or German or Brazilian) transaction and sellers, worldwide, will block the country.
Cross-border shipping is slower than domestic. Fact of life, but some sellers worry about their shipping time DSRs.
All these reasons make Canadian sellers very happy
And welcome to Canada, I hope you enjoy your stay.