Personal information that has been collected about you has a commercial value. It’s actual value depends on how detailed and accurate the information is and whether there is a need for it.
Unfortunately this encourages companies to gather and hoard personal data, even about things that aren’t relevant to their current needs, because it may have the potential to be of value at a later date.
However storage and use of personal data usually requires your consent. Since neither party can predict how that information may be used there is a growing trend to restrict information on a need to know basis. There are also concerns that data can no longer be held securely for extended periods because of high profile data security lapses. This lack of trust reduces the potential value of commercial data collection because less and less information is likely to be shared.
Privacy policies are set out to explain how information about someone is kept and how that information will be used. A key factor in establishing trust with the customer is how long the information will be held. Companies will often put a lot of effort into checking their records on a regular basis because stale data costs money. It is a waste of money sending out a promotional offer to an incorrect address simply because they didn’t know you have moved.