The problem is that every project claims to be buying off the shelf software with some 'minor tweaks'. If it truly is off the shelf, and you're guaranteed that it will be your last sale because after that your work will be in the public domain, then you'd have to send the government one hell of a bill. Things like windows, office, ERP systems, BI and reporting systems, accounting and HR, logistics.. it's more tax effective to buy them as a normal customer.
