I see what you mean. Ideally, you'd have evenly trained and skilled people who can do both climbing and groundwork. Corporate models which best distribute the benefits and share in the burdens will succeed. Seattle will probably be an interesting proving ground for a new wage standard for our industry. Here comes the era of the $500 Japanese Maple prune, and the $3,200 small Douglas fir removal; 1/10th of all bids accepted. May the strong survive!
In addition, because the mandate goes into effect immediately for large businesses, it will create a labor suck into large corporations because even incredibly low skilled work at a big company will pay so well. This policy will hurt small businesses which rely on hardworking people who have been drawn to tree work because it affords a way up out of poverty. Tree workers define themselves partly by the distinction of not being paid mere minimum wage. To ask them to undertake intrinsically harder work than most minimum wage jobs and then not compensate them differently will be an affront to their dignity as working people. The policy will create a labor market for unskilled,positions (the large corporations who must hire at $15/hr) in competition with small businesses (like tree services) which have traditionally relied upon skilled labor hired at the same rates.
So, you see, in order to compete for these people, tree services will have to pay more money. And, accordingly, the next rung up--the climber positions--will have to be that much higher, and the foreman position will have to be that much higher, and so on and so forth. This will lead to price inflation, for sure, and that should cool off the market for tree work to some extent. I am curious to see how it unfolds.