We had testing, and remediation by one company which included duct cleaning, home wipedown, air scrubbing and crawlspace encapsulation. Clearance preformed by the same company with a warranty. Third party confirmation on our end just to make sure. It was a simple process.  I agree the choice of company should be up to the consumer.  Making consumers hire two companies to provide one home improvement will be complicated and cost additional fees and create headaches if problems arise.  Good Idea to have regulations though.  I work as a HUD approved renovation consultant as well. I understand contracting and consumer needs.