I doubt it has anything to do with Canadian pilots in general, its probably more the techniques you were taught. FTA obviously has their own standards and views as to the "correct" techniques, and if your training is different to what they believe, then instructors are likely to say so and try and get you to do things their way. After all, if you pass, you have to adopt their ways, and part of the grading is to see how well you can adjust and even accept criticism (it says this in the FG documents that you get).
FG isn't only about your flying skills (I would highly doubt they would get any ab initio cadets who were the perfect flyers), its also about your attitude, rate of learning, ability to adapt, professionalism and many other things. Sometimes you may pass FG at FTA, but Cathay still may not offer you a cadetship. That is why they have now stopped instructors from giving Flight Graders any form of feedback after each flight.