Thud, I can't speak for the law in Montana but here it is hard work suing the State/Federal governments. When that guardrail was put in place it no doubt met all legal requirements and was standard practice at the time. My department can be sued (and does get sued) and will lose if it can be proved that the design when done did not meet the then standards. In those photos I can't see a flare or energy absorbing treatment that would greater decrease the chances of that accident happening although there may be one there. When dealing with people you never say never. In the last 20 even 10 years there has been huge advances in safety measures that also come at a high cost in many instances. A T-2000 type end treatment that should work well in that case costs around $15 000 + fitting (Australian) and to retrofit all the older barriers would break the road budget where the money could be more useful elsewhere. Again here, if I do any work on a section of road that had the old style that was no longer compliant I would change it to the current standard. It's a bit like your old 68 Ford truck, you are still allowed to drive it on the road even though it is far less safer than the new 2011 model but there is no way you would ever be allowed to bring out a new 68 Ford today.