VIPKid is the latest gig-economy company to be ensnared in the contractor-versus-employee debate. Uber Technologies Inc., which treats drivers as independent contractors, was sued last year in the U.S. by drivers claiming that it misclassified workers, allegedly depriving them of overtime wages and tips. Food-delivery service GrubHub Inc. was sued on similar grounds. Both have denied wrongdoing and are fighting the lawsuits.