Why isn't it used in everyday transactions or why wasn't it implemented?
If you send Bitcoin to a normal address, it simply appears on the blockchain. But if you send Bitcoin to a Silent Payment address, your wallet needs to do much more work to find which funded Bitcoin addresses belong to you.I selected that option in Cake wallet and it seems like the wallet has to download a lot of data to make the whole thing operational. From what I can see, it's quite slow and stops when the screen turns off, so it's not as simple as it seems at first glance.