AS PRESSURE GROWS in Canada to adopt the American justice model of harsh prisons and long sentences, Finland has saved millions and prevented centuries of human misery doing the opposite. HAMEENLINNA, Finland — In a classroom thick with wigs, sinks and barber chairs, a man sprays water through a woman's sudsy hair and works his fingers carefully to rinse the shampoo. Standing in front of a large mirror, another man brushes and sprays a woman's hair. Two others discuss styling techniques. It could be a scene from any community college, but for the bars on the windows.