Ireland introduced a postcode system called Eircode relatively recently in 2015. Controversially it is not possible to map from an eircode to a GPS location without lookup on the Eircode Finder web site. The good news is that Google maps service supports eircodes and does the lookup for you behind the scenes. However, the bad news is that Google has a subtle but significant bug in the way that the Google maps works with eircodes.
The best way to understand the problem is to look at a practical example.
The example I will use is the address "12 Maunsells Park". If you search for this address Google will thankfully translate the address to "12 Maunsells Park, Galway, H91 AVW8, Ireland" where "H91 AVW8" is the eircode. If you ask for directions to this address it will correctly navigate you to the front door.
This is all good. However, the problem happens if you decide to instead search for the eircode "H91 AVW8" (many delivery drivers prefer to search for the eircode because it is shorter to type and is unambiguous). At first glance this seems to work, because the dot appears at the same point in the map. However, if you try navigate to the point you will run into problems.
The problem come from the fact that there is a small lane called "Maddens Lane" running behind the property. This small lane is lined with trees and a tall wall - there is no easy way to get from "Maddens Lane" to "12 Maunsells Park". However, since the dot on the map is slightly nearer to the back of the property, Google incorrectly decides that is where you want directions to.
If you route from one to the other Google says it is a 5 minute walk with three turns as you can see from the screenshot below.
This might seem like a minor nit-pick, but the reality of the situation is that people with a property between two roads like this will frequently dealing with delivery drivers ringing up to say they can't find where to deliver their package.
Understanding the problem is easy, implementing a solution is less obvious. One solution would be to update latitude/longitude in the eircode database to put the dot nearer the entrance to the property. However eircode support neem to be reluctant to do this.