It happens, though rare. I was in the Precheck line at AUS Saturday. There was nobody in line for regular security. I'm not exaggerating, I mean literally zero people. People walked straight up to the document checker in effect. Meanwhile, in the Precheck line, there were at least 8 or so people in front of me when I arrived. Of course, I was through relatively quickly anyway as 8 people isn't much of a line. But, during slower travel seasons (i.e. now for most domestic USA/domestic Canada/transborder travel), when a higher percentage of travelers are business travelers (more likely to be NEXUS cardholders in this instance), sometimes the non-NEXUS line will be shorter. It can also depend on allocation of number of lanes and staffing. YVR has multiple security lines at US transborder. Usually only one or two is for NEXUS. If there are more lines open than normal, or fewer passengers than normal, regular security may have a shorter line. I personally haven't seen this (mostly 15-20 minute non-NEXUS line waits compared to 5-10 for NEXUS line, based on a recent experience when I traveled with two non-NEXUS members), but it can happen.