All bird feet are not the same. One size does not fit all.
Different birds have different jobs in this world, and their feet, one of the main tools for the work they do, have evolved to fit the task.
The feet of the black-capped chickadee coming to your feeder this morning are those of a passerine, a perching bird. About half of the birds in the world are passerines. They have very flexible toes, four of them, three pointing forward, one to the rear.
Woodpeckers also have four toes, two pointing forward, two to the rear. This gives them ready grip and movement on trees. An oddball species found here is the three-toed woodpecker, an uncommon resident in northern Minnesota and elsewhere.
On the belted kingfisher the middle and outer toes are partially fused. This gives kingfishers the tool to dig the embankment burrows in which they nest.
Hawks and owls have four toes widely separated for increased gripping power. Owls can turn their outer toe either forward or backward, an adaptation to improve hunting success.
The pad of the foot of the great horned owl is rubber-like and stippled, aiding firm grip. Ospreys have spines on the pads of their feet. Fish are slippery.
Birds that walk, like the killdeer, tend to have flat feet and long toes. The killdeer belongs to the shorebird family, birds often found on soft surfaces, wet sand or mud. Those toes keep them from sinking.