A lot of it comes down to the mapping problem between the messy real world and nice-ish structured things like relational databases.<p>Almost all of the &quot;identifying&quot; objects about a person (names, emails, even fingerprints can change over time&#x2F;accidents) change with time and circumstance. That&#x27;s hard to encode in a database or program against, so identity is a harder problem to solve than people would like it to be.<p>People like 1:1 mappings because it is easy to map and report, but those are rare in the real world. There is more than one John Smith. John Smith may have more than one email address (at the same time even).<p>Credit Reporting Agencies are essentially tasked with doing an ad hoc mapping of the vast fuzzy cloud of identifying statistics about a person to a 1:1 report ID. It should be no great shock to anyone that the Credit Reporting Agencies will get this wrong sometimes. Sometimes I wonder if its the Credit Reporting Agencies that should just hand out identification numbers (here&#x27;s your Equifax Report #, use it apply for credit from here on out; we will no longer provide results without that specific ID #) and stop trying to corral data that will always be wild and untamable.