There's a reason that most major film unions and guilds have a designated chapter for the Art Department. In Vancouver, the Art Department is somewhat of a disaster, as a result of the lack of independence the Art Department has.
Let me explain. In Vancouver, the union covers all of the pre-production trades. Hence, the majority of members are in the shop trades. The Art Department therefore has little clout when it comes time for negotiations.
The nature of the industry also affects the nature of the operations. Everyone wants to be in the Art Department. And anyone, knowing the right person, can get hired, even though they are not a member.
The latest trend in Vancouver is to hire a young Art Director, a keener, and to expect them to perform multiple roles, or give them a lesser rate, once they have taken the position. This works because the Art Department has no clout. The Art Department members are considered replacable on a dime. The person being hired will only be replaced instantly if they protest.
Hence, the wages have slipped, and, believe it or not, it is not uncommon in Vancouver for the person who is washing buckets, to be earning more than the Art Director.
That was not a typo. Art Departments need their own unions & guilds. Kudos to the cities that have addressed this.