1) If the spa owner requires it, they have to have to have it or the spa owner can likely evict them (e.g. for breach of contract, if the requirement is in the lease; on a month's notice if they are a month-to-month lease for their space).2) Even if not required, it would be a VERY good idea for the contractor to have his or her own insurance, since the spa owner's insurance protects *her*, not her independent contractors.