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The trouble is in the UK we have no official residence. Many parts of the world require you to register where you live (after something like 3 months) with the authorities and keep them updated when you move. That kind of thing has always been resisted for lots of good reasons but it means it is much harder to know who is living here, how long for etc. It's inevitable that when you try and infer residence from a collection of other databases gathered for other reasons it's going to be a mess.
https://www.theguardian.com/uk-news/2020/feb/17/italian-man-95-resident-in-uk-for-68-years-told-to-prove-it
Government administration incompetence strikes again.
Note that Alberto Costa voted against making settled status a voluntary registration process, so irony klaxon for him being so concerned about this.