Let’s try to run through the resource based economy.
Vaults (nodes) make up the network and have many personas. They store data chunks, serve data chunks, their age rank increases with expected/good behavior over time, being promoted from child->adult->elder. The responsibilities of the vaults personas change based on age. As a child you are not trusted with much anything by the network besides being a storage device, as an adult you can handle and store data, as an elder you will sign data and transactions and so on. Of course the software does all of this autonomously. If you constantly lose connection, fail to serve data, or do malicious hacking that is outside of expected behavior, your age will be halved/demoted and eventually can be removed as a vault. When data is requested and successfully delivered from your vault you are “farming” Safecoin.
Safecoin amount rewarded to vaults is adjusted based off from network needs. If there is not enough storage, more Safecoin will be rewarded, if too much storage is available them less will be rewarded. I believe there is some buffer of like 30% of free space across all vaults at all times. The network mints fresh Safecoin for vaults/“farmers“
When a client stores data they pay the storage rate at that given time which is constantly adjusted by the network to be as low as possible. That just means it should be as cheap as storage should reasonably be and competitive without being harmful to the network. What they pay the network to store their data, is then burned, more like buried ;D by the network. There is a max coin supply and recycling of coins helps the network and coin scale sustainably.
When a client requests any data, it is free. That is a fundamental of SAFE for anyone to have access to data for free. When a client requests data it is giving the vault/farmers part of their intended purpose in which the network rewards the vaults for doing so.
There really isn’t anything disparaging in this relationship. What you maybe are taking issue with might be addressed by the following.
In regards to opportunistic caching, as data is requested and along the route of its destination, that data can be cached temporarily by other nodes which when you think about a global network, can help make serving that same popular data you are talking about, faster, more efficient, and less intensive on the network. Vaults just have to fill their roles and I don’t believe opportunistic caching is rewarded. It’s like having any job, you have some things you may not have been hired specifically for that are required of you but if you didn’t do then you’d be fired.
Hope that helps.