NY Ripper/Highlander UK/Stendhal Syndrome etc. video/digital noise?

[Aristide Massaccesi]

First of all I have nothing against grain, in fact I appreciate a healthy layer of film grain. But noise is something else. I've seen it called 'video noise' and I've also seen it referred to as 'digital noise'. So far I've noticed excessive video noise on these titles:

The New York Ripper (otherwise a great transfer)
Highlander (UK)
The Stendhal Syndrome

I also noticed some on The Bird With The Crystal Plumage.

Remarkable that three out of these four titles are Blue Underground releases.

Can someone explain to me what is the cause of this phenomenon? Unlike grain, it doesn't seem to be part of the original film master, rather it's something that is created during encoding. Hence it bothers me somewhat, because it's not supposed to be part of the presentation. Is it a manifestation of compression?