Many SD cards have wear leveling built in, but most of the algorithms and CPUs used for the controllers are quite crap at wear leveling. If you start looking at more industrial targeted SD cards you'll find quite decent wear leveling.
Most of them do some kind of wear leveling, but they usually use cheaper flash and less capable controllers and the controller algorithms are mostly oriented around making them usable for sequential writes as you see with a digital camera, not for making a good drop-in replacement for rotating disks.