Is U.S. Priority International Postage safe?

I've sent 2 packages to Mexico on 2 separate days almost 1 month ago. See attached tracking info. The packages never got delivered. I called the post office and was told there's no tracking on the packages once it leaves the country. Based on the information from the USPS website, there's no evidence it ever left U.S.!

I paid $10.40 for each package and there were some valuables insides as well....of course it was not insured but I want to know if I'm eligible to get a refund for the 2 x $10.40 or $20.80 at least.

Is the U.S. Post Office responsible for lost packages on Priority International Mail?

The U.S. Postal Service was electronically notified by the shipper on March 28, 2009 to expect your package for mailing. This does not indicate receipt by the USPS or the actual mailing date. Delivery status information will be provided if / when available. No further information is available for this item.