By Daniel Wiessner (Reuters) – Southwest Airlines Co cannot force a baggage handler’s class action lawsuit over overtime pay into private arbitration, the U.S. Supreme Court ruled on Monday in a decision with costly potential implications for companies including Amazon.com Inc and Uber Technologies Inc that employ many transportation workers. The justices ruled 8-0 in a decision written by Justice Clarence Thomas that baggage handlers are engaged in interstate commerce because they routinely load cargo onto planes that cross state lines, exempting them from a federal law that requires the enfo…