Flying from MSP - YVR and DL GA insisted she would not let me on the plane because my Nexus card did not have an "airplane symbol". This is an example of poor knowledge and poor training - no such symbol exists and is not required. I have flown non-DL before and just my Nexus card was just fine (I also have the iris scan). I do also carry my passport with me as a backup, but it should not be necessary.