Old cars are often used to source parts for the repair of other cars. It's common practice, which has persisted without any major problems. Likewise, 3rd-party

Old cars are often used to source parts for the repair of other cars. It's common practice, which has persisted without any major problems. Likewise, 3rd-party repair shops will often harvest parts from old phones, to replace parts in phones they are repairing. Picking and testing components doesn't appear to be a problem for them. Their customers seem to have no issue with recycled parts being used to repair their phones. If there is demand for recycled parts, and they can be reused while still ensuring quality, what is the problem?