1.) The field is huge. The deer can come out anywhere and be out of range at all times. The pile of corn assures they will be right under your stand.
2.) The field is there 24/7 for months. Deer can come in the middle of the night if they choose. The field cannot be set on a timer to be available at 7:00am and 3:00pm.
3.) The field is in a fixed spot. As the season changes, and deer move into different areas, you cannot put the field in a bucket and bring it with you. It's there.
4.) Deer don't like standing out in the open in broad daylight. You can pour corn in the thickest of cover.
5.) Fields go through stages. Sometimes the greens are not palatable. Eventually, the deer burn it out. Corn can always be replenished, as needed, and it's always ripe.
6.) Food plots require spraying weeds, removing rocks, disc plowing the soil, putting down lime, planting seed, fertilizing and waiting......desperately hoping for the right mix of rain and sun and hoping you get a nice green field in several months. Bait is a little trip to the local co op.