This seems ludicrous to me. It is all-too-often a matter of passing the buck. And as the floor covering contractor is generally the last person on the job, it is easy to blame him or her for other trades’ failures to follow through on their responsibilities. Last on the job, last to get paid and, if a project runs short of funding, an even-longer wait for the check.
This leads me to suggest that the responsibility for these items should be spelled out in the contract. It is worth spending a few dollars up front for a good attorney to review your contracts for you, making revisions when needed, to help protect you from unjustified claims and lengthy waits for payment.