I have been spending some time under my truck touching up the undercoating for winter and have noticed serious corrosion on my lines, too. With all of these failures you guys tell of, my doubts about those cheap tinned factory lines have been confirmed. I don't think I want to wait for that crucial, and potentially life-and-death, panic-stop to discover they no longer can take full pressure.
InLineTube is a company that offers stainless computer pre-formed lines for many vehicles. They make the lines I'm putting on my '69 Camaro (brake and fuel). They also sell them made from the original tinned steel for the "purists", but I don't care about "show points" compared to safety and longevity. A complete kit is only @ $150 to $200 for the Camaro, and that is every inch of every line, including the rear axle lines and master cylinder to proportioning valve.
The difference in price between stainless and the cheap tinned steel is so small given the consequences of failure, that I agree stainless should be mandatory. Your life is apparently not worth those few extra dollars to the manufacturers. I would gladly trade any number of inane electronic gizmos today's vehicles are overloaded with for better basics, like brake lines that don't corrode and blow out when you really need them.
As for accepting that things wear out, that is true. But we are not talking about moving parts here or a simple roadside breakdown if they fail. Brake lines should be of premium material, not "corporate cost effective" material, especially given the numerous stories of failures posted just here. Note that the rubber brake hoses, that actually do move and flex, are outlasting the stationary steel lines. That speaks volumes.
Would you fly on an airplane with hydraulic lines made from the same cheap material and exposed to the elements? There is little difference in outcome between hitting a semi at 70 mph and hitting the earth at terminal velocity except for the news coverage afterwards.