@bafanguy , yeah I bet the fact that Expressjet is union and Skywest is non-Union has a significant factor in this.
@DeltaT , many of the U.S. regionals fly into Canada. Skywest flies to Canada, Mexico, and the Bahamas but the 90 day VWP will get you in trouble. Visiting crew members must possess a C1/D visa to enter the US. Foreign crew members do not enter on the visa waiver program when on duty.