I completely disagree. There is a bidding process. Specs are handed out by the buyer. I submit a bid that conforms to specs, I win, I build. I've done nothing wrong if I conformed to my bid. I don't make the regulations, that's not my job. I fail to see why I should bear any responsibility whatsoever in that case, again, assuming I conformed to the specs I was giving during the construction process. The responsibility lies solely with the regulators assuming all other rules, regulations, by-laws and procedures were followed properly.
I renew my contract every couple of years with my local municipality and I'm routinely asked to do things over the next couple of years that aren't in the contract and I simply refuse. Even simple things that might take a few seconds, like turning a screw, that I have done on a regular basis for my other customers I won't do because I know, if the poop hits the fan and something goes wrong, the first question asked is going to be, "who did this and were they authorized to do this?". I made that mistake once and only once, never again. The word of a disposable, replaceable contractor vs. the word of a career gov't employee. We all know how that is going to turn out, my head will roll there's no doubt about that. I make a virtual and/or a paper trail, inform the right people of the work to be done IMO, and cover my ass. All the contractors know each other and we all do the same thing. Assuming they did the same thing in this case, they should have zero responsibility for the outcome.