A TomTom (a totally different device) uses a different set of maps, receives data and even creates routes differently.
As an example, you can sometimes see this in action when you create a route in MyRoute’s default HERE maps. Sometimes in HERE, MyRoute will refuse to take a road for no obvious reason. However, if you switch to TomTom’s maps, routing down the road is possible, as TomTom‘s maps do not know that the road is closed. Similarly, MyRoute has the ability to compare a route created in HERE with how the same route would be displayed on a TomTom device. It is surprising by how much they sometimes differ.
Obviously, if neither the Garmin device or the TomTom device (both set to receive live traffic data) do not receive a notification across the ether that a road is closed, neither of them will know about it. Similarly, if neither or either device receives an update that a road is now re-opened, then the device(s) will not know about it. By preference, I have turned off (or have set to prompted) all re-routing and all traffic updates; but that’s just me. I find this removes several variables, a lot of which I have no control over whilst I hoon along.
Journeying about with a ‘large group’ is sometimes not particularly easy, as so many variables creep in. Sometimes, it’s as simple as bods having no idea at all how their navigation device works. This is before we even get into unique preference settings or that some devices (from within the same manufacturer) operate differently than others, I long ago gave up listening to bods on a Wander waving their arms and saying “My device tells me that I should have turned left back there“ or ‘My device is keeps telling me to leave the motorway”; to be honest, I really don’t care. All that matters to me, is that I (think) I know where I am going. If their device says something different (for possibly a whole heap of reasons) I am not going to stop every five minutes to find out why.
What I did give up long ago, was shouting at a GPS device. I gave up when it suddenly dawned on me that it can’t hear me, any more than a map or an unexpected road closure sorrier can hear me either. Sometimes I do have to stop to simply help the dumb (but really very clever) device along. But that is very little different to me stopping to turn over a map, which (being nothing more than ink on paper) is equally dumb…. And quite clever, too.