Unless you are crossing at the same port of entry on a very regular basis it's hard to generalize an individual agent's attitude into a statement about CBSA more generally. There is a trusted traveler program in place for frequent travelers, if you are entering Canada from the US often enough to have an opinion about YVR immigration you should consider joining.
At the end of the day, visa-free entry to a foreign country is a privilege. If you do not understand this perhaps it is the traveler's attitude that is causing the problem. You try giving attitude to a US CBP officer as a foreigner and let me know how that goes.