No one enjoys boarding an airplane. It’s slow, it’s inefficient, and often undignified. And that’s without even getting into the ethical quandary of so-called gate lice, the anxious passengers who cluster at the gate before their group is called. But at least one part of the process doesn’t need to be disrupted. When it comes to shunting slow-moving passengers to the front of the queue, such as those requiring assistance or with small children, the airlines have it exactly right.