The Big HavaHeart live animal traps that I have are the two door variety. So it looks like you can walk right though it. When the trap door on the floor is stepped on both the doors on each end of the trap slam shut and are locked in place. HavaHeart has some traps that are single door like the ones you show in your photograph.
Yeah they make both kinds.I've got a little miniature 1 for mice,rats,chipmunks etc that is the 2 door kind,it's a cute little thing. I've been mainly catching shrews and sparrows in it though and a few mice.
Both 'possums and 'coons are on the hit list here. I had fish food in the cardboard shipping boxes in an outbuilding. 6 boxes so far this year have been torn open, and the inner bag has been opened up too.