A Proofing is standard good business practice in the printing industry. Proofing ensures accuracy, reliability, and consistency. It takes more time up front, but guarantees professional results. We could fax a proof, but we'd rather not. Faxed proofs are often difficult to read - and when you are looking at punctuation, very unreliable.
Faxes also change the size of type and make inspection of sizing and placement nearly impossible.
A fax will do for a second proof, on occasion, but should not be used as sign-off for a first proof.