The Olympic sum of money

The public accounts committee has criticised the government for seriously underestimating the cost of the London 2012 Olympics.  They have said that better management of the construction project is required if the cost is not to spiral higher than £9.3bn. It also expresses concern about the legacy use of the Olympic Park venues in Stratford, east London, and the drain of National Lottery cash from other good causes.

The report produced by the committee has stated that "A-ny slippage in delivery of the programme ... would run the risk of having to pay more or reduce quality to be ready on time... The costs of the games were seriously underestimated at the time of the bid and the private sector funding seriously over-estimated-."  Why can't the government ever estimate the cost of anything correctly?  Why do they always underestimate their costs?  Why do they never heed warnings?  This isn't the last we'll hear about spiralling costs...