Travel to the US has become quite expensive in terms of taxes. Look at these charges for an Aeroplan redemption to Chicago. I checked Los Angeles and it wasn't much different.
U.S. International Transportation Tax $49.00
U.S Agriculture Fee $5.20
U.S. Customs User Fee $7.60
U.S.A Immigration User Fee $9.20
U.S. Passenger Safety Fee $7.40
U.S Passenger Facility Charge $5.90
The Canadian ones pale by comparison:
Canada Domestic/International Air Travel Security Charge $12.10
Canada Goods and Services Tax $2.11
Canada Domestic/International Airport Improvement Fee $38.00
Canada Harmonized Sales Tax $1.04