ID requirements are not a whim of eBay's, but part of legislation that governs the payment system eBay has transitioned to. There is also legislation surrounding data retention and security that eBay must comply with - to put that in context, you have already given permission for any eBay rep to access your account data in appropriate circumstances, like when you contact them with an issue and they ask you to confirm your details - they are checking your responses match the data they have, but this would not be your ID, or bank account info - that is stored and encrypted. In fact unless you send through a visual copy, it's doubtful any human would ever clap eyes on it, rather your identity would be electronically verified.
If you're genuinely worried about how your data could be accessed and used, I'd recommend asking your local government representative why we don't have a federal human rights charter, one that protects and grants rights to us over our own data, like other countries have.
