I assume that you mean American carriers aren’t using the linked Embraer, because Porter flies it between the US and Canada a lot. For example, their LAX/Toron

I assume that you mean American carriers aren’t using the linked Embraer, because Porter flies it between the US and Canada a lot. For example, their LAX/Toronto route as well as most if not all of their routes from Toronto to Florida. They generally only use their De Havilland turboprops if the flight operates out of Billy Bishop instead of Pearson. The advantage of Billy Bishop is that you can literally walk to the Rogers Centre or the CN tower in less than 20 minutes from Billy Bishop, so that’s a decent trade off.