If the issuing TA doesn't charge YQ no one bothers if the plating airline autopriced incorrectly. Thats what happened in the first wave of the PL 'trick' when UA fares plated on US stock didn't have YQ in them. I know of LH ticketing agents who saw these tickets but didn't hinder the pax as it was US messing up the YQ collection. See the ORP YQ thread about details who is liable for collecting the correct YQ.