Fist off.. I completly agree with you that in this modern day and age a company should be able to keep electronic records of my transactions with them.. even 5 years ago they should have had that ability.
Most companies have policies on warranty ruturns that are based on the laws of the state or states they opperate within. Usually these are based on the
Set of standardized state laws governing financial contracts. Called the Uniform Comercial Code dating back to the 50's when paper documents were the norm.
The code was drafted by the National Conference of State Law Commissioners, and was adopted in the 1950s by most states and the District of Columbia. (Louisiana, the only state which has not fully ratified the code, has adopted Article 3 of the UCC, dealing with Checks, Drafts, and Negotiable Instruments.) The code has nine separate sections, called articles. The most important of these are Article 3, dealing with negotiable instruments; Article 4, dealing with bank Deposits and Collections Article 5, dealing with Letters of Credit Article 7, dealing with Warehouse Receipts and other documents of
Title and Article 8 and
Article 9, dealing with Secured Loans.
http://www.law.cornell.edu/ucc/7/
It has been re-written and updated for todays electronic commerce but not all states have accepted the amendments.
Since most companies policies are some what flexable it is sometimes possible to have it overridden by customer service. Also some companies will provide a copy of that required document, for a small fee of course, so that the return may be processed per thier policy.