> from more than a few inches away Nah, you can always crank up the power in line with the inverse square law. Your other reasons are plausible. RFID tags are

> from more than a few inches away Nah, you can always crank up the power in line with the inverse square law. Your other reasons are plausible. RFID tags are fairly cheap, but they can't compete with printing a barcode on a label.