...At the same time, I don't think its necessary for Ledger (or any other hardware wallet manufacturer) to keep sensitive information of their customers for long periods of times. I would have expected information to be scrubbed regularly.
I can think of a couple of reasons, the company's accounting since it is supposed to record everything (payment details,date, and so on).
But also simply to be able to provide assistance to the customer. I mean for example if you have to be reimbursed for your wallet (for x reason), they have to keep a trace of your order (including your name, method of payment or other).
Otherwise how else could they be sure that you actually bought it on their store and not on Amazon for exemple.