On the Japanese telly a couple of days ago they had an article about the latest issue - places, even within the same town, can have the same name, or the same kanji but different pronunciation, or people have different ways of writing their address - 1-2-3-4 is actually identical to 一丁目二の三番四号, but the database requires an exact match. One could use the post code which would eliminate 99% of these ambiguities, but the My Number system does not include post codes for whatever reason.
Yes, I was facepalming that they only just realised this, and it will take them another two years to hook up to some master database of official addresses, although that doesn't address the other issue of needing fuzzy matches.