Yeah, my complaint was with the article. Why leave out such an important piece of information? Why not dig into the agreements and understandings? You say it is obvious, but to me it is not. I know of several works of wall-sized graffiti and similar that just had a verbal agreement, which would be very vulnerable if the property got new owners or management.

As I understand it, here in Norway the propery owner would be entitled to destroy the murials entirely (but not alter or mutilate), by say painting over them in entirety. However they should then notify the copyright holder (artist) in advance so the copyright holder has time to document the murial.

Sounds like this wasn't done, but I don't know if there are similar laws over there.

If they had verbal agreement it is not graffiti.