(asked for some more info through support ticket #338590)
Just for clarity I'm currently uploading this scene into the support ticket. It took about 1 minutes to model this and successfully reproduce the artifacts.
The reality is, to get rid of the artifacts on the box, I'd need to make every quad as small as the 10mm shadow gap I've modelled in. The box is to represent a building, the shadow gap is to represent smaller details that are often used in building design. Especially the all white rendered/stucco villas I spend a lot of time working on these days. The box in the example isn't even that detailed in comparison to a whole building and the artifacts are already visible. Now imagine a full modelled building
To fix the ground plane, I'd need to use quadremesher (or similar) to get a dense mesh before those artifacts go away but again that's not really how the vast majority will be modelling simple flat roads for commercial arch viz, they'll be tracing (or directly using) splines from CAD drawings.
It's just a huge time sap trying to use displacement in Corona. You need to make sure your meshes are absolutely perfect, with perfectly distributed uniform quads and absolutely nobody models buildings like that. I often model my buildings, especially these fully rendered villas as one complete piece (screenshot below) because, whilst the underlying structure isn't all connected as one complete piece, the trowelled render over the top of it all usually is and this method enables me to get those lovely chamfers in all corners and crevices. The same applies to internal plastered walls, all usually modelled as one piece to get those nice chamfers between walls and ceilings as you would in reality etc. So keeping everything as uniform quads is not practical in the slightest.
Maru - the example you've sent in the email where you've tried to replicate it is too basic when compared to the reality of a production quality full building model. Also I'd be confident enough to say you have got some artifacts. Try applying my override shader to it from the scene I'm uploading.