The legislature tried to create language specifying what the liability should be:
RCW 64.06.050
Error, inaccuracy, or omission in disclosure statement — Actual knowledge — Liability.
(1) The seller of residential real property shall not be liable for any error, inaccuracy, or omission in the real property transfer disclosure statement if the seller had no actual knowledge of the error, inaccuracy, or omission. Unless the seller of residential real property has actual knowledge of an error, inaccuracy, or omission in a real property transfer disclosure statement, the seller shall not be liable for such error, inaccuracy, or omission if the disclosure was based on information provided by public agencies, or by other persons providing information within the scope of their professional license or expertise, including, but not limited to, a report or opinion delivered by a land surveyor, title company, title insurance company, structural inspector, pest inspector, licensed engineer, or contractor.
But the point is more creating some certainty for buyers and sellers. The NWMLS language regarding Form 17 liability is absurd, and now there’s this wrinkle in the case law which may or may not fly in the future if someone tries it. People need more certainty. As for not being able to waive it, this is in essence consumer protection, and non-waiver is provided for all the time–look at the distressed property law.