I do a lot of work with RFID. Companies like Fieg etc have made some awesome advancements in Tags and Readers.
I have Tag samples costing a few cents to many $s. Some that work only on metal or glass or ALL types of surfaces.
I have readers that read to 1M, 3-5M, 10-20M and 40M !! Some at up to 100s Tags a second. They have come a long
way since my first systems 20+ yrs ago. But, for all that, they still have one enduring weakness, very easy to shield.
SO, If your application is "looking for stolen items", thieves already know how to get around it.
Otherwise, it's definitely a technology that has it's niche. In one application, 4 Readers are set up on 4 corners of a
large plant entrance. As forklifts drive in out out with pallets of goods, ALL items are read instantly, with no speed
reduction required. I've tested similar applications, can't do that with barcodes :-)
Edit: One tag type I've been using is designed to work - stuck on the inside of a metallised windscreen. It uses the
windscreen itself as the "tuned antennae". Many tags now are designed for direct metal placement, and these are
VERY thin paper tags !!