Slightly different spellings of names (Ant Mars Smith vs Mark Tony Smith-Jones), ways to write addresses (house name vs road name), etc will make automatic join

Slightly different spellings of names (Ant Mars Smith vs Mark Tony Smith-Jones), ways to write addresses (house name vs road name), etc will make automatic joins difficult. Such inconsistencies do not significantly affect the ability for humans to use the records. Then it's just a matter of making sure that everybody with the skills to do so, either refuses, or does a bad enough job to sabotage other parts of the process. (It is not hard to think of these, so I will not discuss them here.) Making the job legitimately difficult makes it easier for people to refuse to do it, and makes it more likely that the bad guys who try will find that they actually can't.