When a product is developed, there's a stage called requirements, writing and gathering. In terms of the time it would take to work between the government and the contractors, that's different from someone saying, this should be fast because I handed you what to build. I think there is a relevant process time in that number.
In terms of the rationale for the cost, without seeing how this went down, I couldn't speak to it. But I want us to remember that what we don't get when we fail to invest in a public service is reuse. If we're spending this much money, we should be investing into the capacity and code with conditions that we can reuse as the federal government. This to me is a bad spending decision regardless.