Powder coating as a rust treatment is not understood by the public. I like powder coated bike racks but I don’t like the way powder coated bike racks are marketed to consumers. Many cut-price merchants sell powder coated bike racks – they refer to ‘tough’ or ‘durable’ powder coating. The emphasis of these merchants is to make a product as cheap as possible and sell them in bulk.
The problem is that eventually the powder coating will chip or crack and expose the steel core to the elements. The raw steel will quickly start to rust, but usually after the warranty period. If it is after the warranty period then the consumer is usually stuck.
You see the problem is that powder coating does not (by itself) protect steel against rust. It is the same as painting your garage without undercoat or laying carpet without underlay. It may look OK, but quickly deteriorates.