The thing is, Blender treats the geometry from an Object Info node differently than the one from a Collection Info node - because you can decide if multiple objects in a collection should be manipulated together or separately. The Object Info node's Geometry output gives a mesh, while the Collection Info outputs instances by default.
So to make it work for the Collection Info node you have to use a Realize Instances node before the Transform node:
By the way, if the way the Transform on the Collection Info node works would have been the desired result, you could achieve that for the Object Info node as well if you go the opposite way, make an instance of the object. In this case you comfortably have a checkbox As Instance on the node: