It's funny you should mention genetically engineering rice to prevent vitamin A deficiencies. That was actually done by university researchers using an EU-funded grant, the terms of which required them to patent it and give exclusive patent rights to a private-sector company. Said company (one of the big agrobusinesses) decided it wasn't commercially viable and shelved it - but they didn't want anyone else making money from it either, so now it's basically useless until the patent expires. They granted a license for "humanitarian use" but it's so narrow as to be almost worthless except as a PR tool to accuse anti-GM activists of wanting third world malnutrition. (Very few of the countries allowed to grow it can actually grow rice, and it forbids import or export.)

To be honest the whole thing was ill-conceived on every level anyway, but corporations and patent law alone were enough to doom it.