That's a good question. I do not mean to suggest that I can climb into anybody's head here, but there are indications, and I think that it is worth a wee bit of speculation to pull them together for a single picture of sorts.
We is an interesting term here. Different parts of who we might refer to had considerably different information. This is true even within the industry. This industry distributes information in-house on a remarkably strict need-to-know basis, and the need refers to what the owners need a person to know, not what the person might need him or her self. So an engineer will be informed of things that an executive of one or another level might not, and vice versa--and these things are often in direct contradiction. The person who cleans out the pressurizer unit gets a considerably different story.
The public was told that we (that word again!) would get nearly free and nearly unlimited energy. We were also told that the development of the "peaceful atom" would increase security because it would go hand-in-hand with the responsible development of nuclear technology for military use, and because this would create relative energy-independence for the US of A, so that we would not be reliant on uncertain petroleum sources. GE in particular gave film-strips and other media materials to news outlets and schools to support the idea that the population was being cared for by bright, optimistic, rational types like Reddy Kilowatt
At least some local power entities--the companies that hired the plants built--have claimed to have been approached by the government with similar arguments. This is a self-serving claim that I can neither verify nor disprove. But it appears to fit what information is available: energy companies were apparently told that they would be able to continue to levy a fee for service and have almost no technical or hardware overhead after some certain point.
Companies approached insurance companies, of course. The insurance companies said that they could not responsibly insure any nuclear plant at any price because they could not come close to paying off in in case of an accident. Government responded by limiting liability. So, essentially, in effect, the people mainly held culpable for the failure of nuclear plants are the nearby populations. There is some responsibility by insurance companies, primarily to the company owners.
Of course, were a large case to be really tried with anything like full information, the results would not likely be so straightforward, and would be presumably quite difficult for owners, but not in anything close to the measure of the actual problem.
So encouraged, companies made huge investments in construction of plants. Many of these investments were made after pretty much all of the problems were thoroughly known in at least part of the industry.
There were considerable changes in official policy regarding how dangerous how much emissions of which things might be. Allowable emissions amounts in some cases changed by factors of over 100,000. Now, at first glance, such a factoid might give one sympathy for the industry. Investors and executives are told that they can have a containment built to some certain specification; midway or later, this is revised considerably, and the containment has to be torn down and rebuilt. On consideration, one might note that this does mean that the decision is made to produce something for money despite not knowing the danger of the substances involved to a factor of 100,000.
Of course, there was some disagreement over who was supposed to have known, and when.
That leaves a few possible explanations that, in some combination, probably cover many people:
- They were told they were getting free electricity
- The were told that they could sell free electricity for money
- They thought that they were covering for military necessity
- They thought that they could get money by convincing people of the above or just not wising people up
- They thought that they could centralize great military power by convincing people of the above
- They were afraid of revealing the falsehood of any of the above because of threats
- They had made large investments in this technology, and did not wish to lose them
- They saw that government and large blocs of industry were heavily invested, so they figured that they were safe to go ahead because there were other people to take the blame and because people are easy to fool anyway, so the story goes.
There are probably twists for each individual involved, but I suppose this describes the drift.