This surprises you? Have you looked at the ages of most of those agents? In the summertime you are more than likely to get a college kid who is there for a summer job. On your next arrival into YVR, look around. You will find college age kids at the desks and an older officer standing back overseeing everything.

As a non-immigrant visa holder myself I know more about the ins and outs of the system than they ever would. This came to a head last summer when due to a clerical error of their own making I was told I didn't qualify for renewal of my visa and that my previous two visas had been issued in error!
Knowing that they were wrong I stood my ground, my entry was adjourned and they admitted their mistake a few days later and issued the visa.

The grunting and grumbling officers of the CBSA make the US CBP look like consummate professionals.