Trying 2d pathfinding with the A* package-- can this be done without using 3d colliders?

Just what it says on the can: everybody speaks about the A* project like it is the solution to 2d pathfinding, yet all the examples I find use 3d colliders. This seems... intuitively wrong to me. Am I missing something?

 

Short answer...no. You have to have colliders on any object (player character, npc, animals, etc.). Need colliders so character knows its on the ground/terrain, for detecting walls (obstacles), other AI, etc.