All they need to do is look to the sideline and get confirmation that they are lined up properly. The WR made a mistake and the team paid for it.
What I'd like to see enforced more regularly...o-linemen lining up in a "V" formation. Center, then the guards lined up at the center's hip, then the tackles lined up at the hip of the guard. Some teams (pro and NCAA) really stretch this and it gives them an advantage in pass protection. Throw the damn flag.