When a contractor uses only "independent contractors" the first contractor is using other small business owners. The painting contractor who uses only "independent contractors" instead of employees to swing the brushes is avoiding the obligation for employment taxes and other employee related expenses, but those expenses are then just pushed onto the "independent contractors" swinging the brushes - they don't disappear. Instead of the Social security tax being split between the contractor and the brush swingers, it all falls on the brush swingers. Instead of having workers comp coverage the "independent contractors" swinging the brushes need to purchase disability insurance to cover their exposure to work related injury.
Thus, if all parties involved in the contract act prudently then the cost to the consumer isn't going to be any less regardless of whether the contractor uses employees or independent contractors to swing the brushes.