I understand that one way a merchant would likely use Bitcoin is to create a unique receipt address for every customer, so when a given address receives payment, the merchant can know exactly which customer sent in payment.
Ideally, these addresses would get used one time, and then thrown away. But the world isn't an ideal place, and customers sometimes (frequently) make mistakes.
To prevent Bitcoin loss, would a merchant need to keep every address (and associated private key) forever? Doesn't that become burdensome?