I'm wondering this as well since my wife is currently scanning a lot of old family snapshots into digital files. Scanning software is usually tied to the manufacturer of the printer and has to be compatible with the auto-feeder. Photos are variable in size and thickness and I could see it frequently jamming an auto-feeder.
We're using an HP Inkjet with the flat-top platen without an auto-feeder. So it is painstakingly scanning one at a time.