"Most Government Projects are managed under PRINCE2 Methodology which was released in 1996 and which replaced PRINCE which came out in 1986 "
PRINCE2 is a general purpose project management methodology. It doesn't actually dictate the software development process - merely the means of managing it. Most modern commercial software is developed using one or another form of Iterative and Incremental development techniques. This gives much faster results, and is far more responsive to changes in the users needs (and perceived needs).
Ask most people with experience of tendering for public projects, and you'll fin that by the time experts in software development get involved, there is a specification already in place - often a quite unrealistic one, based on the wishes of non-technical people, politicians, civil servants etc. As an expert you then have two choices: go with the flow and tender for a job that you know is going to fail (but at least you'll get paid for it), or point out all the faults with the specification, and get passed over.
As we know from experience, the big software contractors are regularly involved in spectacular failures, but they always walk away with a large pile of dosh, and they are always back on the list to participate in, and profit from, the next big failure.