I'm not sure what you're seeing but you're definitely not seeing genuine AirTags 5 for $13. More likely you're seeing the AirTag holders for that price.
> you're definitely not seeing genuine AirTags 5 for $13
I didn't see anything in the comment which suggested they were. It is specifically points out there are devices not produced by Apple. Third parties can create compatible devices:
That person specifically noted and gave you a reference to how those 3rd party tags use Apple's own network.
What is the clear reference? One person said they searched GPS tracker tags on Amazon and the other gave a link to Apple’s licensing program which in turn links to NDAs and contractual agreements as well a multi-step design and approval process. There seem to be some knock-offs claiming they work with Find My, but there’s all sorts of weird counterfeit crap on Amazon. Do you have links to a product that’s actually licensed/supported by Apple (ie works and will keep working), because that’s what surprised me.
https://www.apple.com/shop/product/HQF72ZM/A/chipolo-card-sp...
I own one, and it works just like an airtag and appears in the find my app. It doesn't have precision feature but everything else works(like using the apple/iphone network to find it)