I offer this feature merely as a starting point for discussion or a call for data points - there's obviously nothing any of us mortals can do to fix up the maps. I'd also point out that I'm not just talking about Maps under Windows 10 Mobile, the same old maps are shown when querying Bing Maps on the wider Internet in a web browser.
An example, then, from a road I know like the back of my hand. It's the A358 near Bishops Lydeard in Somerset - there used to be an infamously dangerous road junction where there have been some fatalities. I'd describe it to you but I don't really have to as HERE Maps data on our phones and web browsers effectively acts as a time machine, showing the junction as it was before 2017 (below left):
Note the offset side road access onto what is a very fast A road, with car speeds of 60mph typical. Very dangerous. So work started on a new roundabout in 2016 and this was completed in May 2017, around 8 months ago. In fact, as shown above, right, if you overlay the traffic layer in Windows 10 Maps, the roundabout is shown perfectly. So the traffic data supplier is up to date, at least. Just not the base maps.
As further proof, here's my view of the junction above - very definitely a roundabout there, wouldn't you say?
(Don't worry, I took this safely with a phone with 'quick' physical shutter button (IDOL 4 Pro), so my eyes never left the road and my right hand never left the steering wheel!)
Now, one missing roundabout doesn't make for bad maps, necessarily, but this is simply one high profile example that I can point to. In fact, again using local knowledge, there's a new bypass in Taunton, taking people from East of the town, to the railway station and then out to the West, it saves a huge amount of time in traffic. It was completed in July 2017, so around six months ago. It's nowhere to be seen in Microsoft's licensed maps.
In the UK, at least, the maps come from HERE and so I went and checked HERE's web site and online maps. They are missing the new road, but, curiously, they do have the roundabout mentioned above, and the new road too (though misleadingly shown, which is why I missed it at first - it doesn't really intersect with Station Road!)
So we have joint responsibility for the outdated maps on our phones (and laptops), I think. Microsoft, despite updating the copyright notice in Maps, for the HERE data, to '2018', is actually using HERE maps data from, I suspect, the end of Q4, 2016. Is this a licensing thing? Is someone at HERE not talking to someone at Microsoft? We should be told!
It's not good enough, it's really not. Apple Maps and Google Maps have had the roundabout and new road for many months. Do you agree that Microsoft isn't living up to expectations here?