[rovek]

I don't know if there is a "main reason" for all instances. For me, on this kind of project at one of the Biggest Co's, it seemed a bit like the safety net point you make and it creeps into everything. There didn't seem to be much pressure because the project was never going to be pulled and had infinite money. This seemed to manifest in "good people" (my opinion) working at about 40% capacity and new hires having a background in companies more like BigCo than InternalStartup.

Edit: To clarify my last point, my assumption being that the point of InternalStartup was to allow deviating almost entirely from BigCo's approach to everything and that those people from OtherBigCo would be less likely to have that mindset.