Drainage is in the eye of the beholder maybe? I used window screen at first, and more organics, and the trees did NOT do well. They were dry on the top, sopping wet on the bottom. Yes, the water would come out, but it drained really slowly. However, maybe with a flatter/wider pot, with lots of holes, and if the trees are tolerant of wet feet, they might do fine. The first summer I had the little elm, I kept it sitting in water for days at a time because I couldn't remember to water it regularly. It survived, and still does, but could have been a lot happier if I hadn't done that.
Anyone can make anything work. (Doesn't Naka I suggest using pot shards to cover the holes, or is than another older book? So many books!!) If the window screen works for you, then go for it. I like the plastic canvas because you can put wire through it easily, anchor the tree in by using wire passing up through it also without making it fold in on itself; the plastic canvas is also reusable and strong. The drainage is excellent as well. As the old saying goes "there's more than one way to skin a cat!". Whatever that is supposed to mean.
Joanie