There are more types of plants than just corn. Trees are much easier and cheaper to establish than solar for example.
Also, if your desired output is electrical power, you’ll lose more energy converting your trees to electricity.
On the plus side for trees, storing the energy they stored is cheap, and can be done for centuries.
The net effect is that PV cells are more economically viable than using photosynthesis to catch solar energy (at least for now; there’s work being done on improving photosynthesis; I don’t see that beating PV soon, though, certainly not because PV cells keep improving fairly rapidly)
And if you collect only the wood, it's a couple of magnitude lower than it.