"if eBay automatically converts pricing on .COM to USD, "
eBay does not.
For example, take a look at 220337545096 on eBay.
com (where US buyers shop). I have used an unsold listing priced in Cdn$ for demonstration purposes.
You see a Buy-it-Now price of
C $130.00 with an approximate conversion in small letters "Approximately US $104.85".
Now, the US buyer decides US$105 is OK and buys the item. He pays for it immediately with his credit card through PayPal. His statement arrives a few weeks later showing a purchase of $108.00 or more (not the US$105.00 he agreed to pay). The difference is the exchange conversion spread charged by PayPal or his credit card issuer.
Do you have a happy customer? Of course not.
But that is besides the point. At the end of the day, because buyers (or their friends or family members or co-workers) may have lost on exchange conversion previously, many potential buyers simply ignore listings that are not is US$.
.