You 're right that you can't express it in the tip (assuming the better wages - lower tip amount model that is part of this discussion), but (as mentioned above) you could choose not to return to a restaurant. You could also take the time, if you so desired, to contact the restaurant management telling them why they are losing you as a customer. It then becomes the responsibility of the owner to figure out how to keep his business open by dealing with his/her staffing issues.