In some situations, the 'vehicle player' command returns the player object, rather than a vehicle object, even though the player is in the driver seat of a vehicle.
I first noticed this issue Friday (27.03.15), while working on a part of a mission I am developing with some friends. The mission is a Capture the Island game mode, and as part of it, two unarmed MRAPs are positioned for each team at the start of the mission. When I, or any other player, enters these MRAPs, the 'vehicle player' command returns the player object, as opposed to the vehicle object.
This behaviour is peculiar, and as such I sought to reproduce the problem. I made efforts to disable any mods that were running in my game, and created a new mission in the editor with one playable unit. I launched the mission and used the console to execute the createVehicle command to spawn a Hunter MRAP and a Pawnee helicopter. I proceeded to enter each, and tested what the 'vehicle player' command returned. In both vehicles, the player object was returned, rather than either vehicle object.
I cannot fathom how the vehicle command could return the player object when the player is in a vehicle, unless the internals of the command have been somehow broken.