Many (most?) trees are efficient at making seed, but what they really lack is the ability to get those seeds far enough away that they won't be out-competed for

Many (most?) trees are efficient at making seed, but what they really lack is the ability to get those seeds far enough away that they won't be out-competed for nutrients, water, and light by the parent tree. Somewhere downhill and relatively nearby is a 'solved problem' for most trees -- but uphill, further afield, with appropriate soil depth for the seed size, in sufficient numbers, with less competition, etc. Aside -- ridges are one of the most useful places to focus reforestation efforts, in no small part because once established there, trees can generally propagate themselves across the rest of the slope. Fending off predators is a concern, of course, but that's why you go for the large quantity approach when propagating by seed. The claim these things can 'plant 100,000 trees a day' is clearly hyperbole. What they can do is plant 100,000 seeds a day, presumably at a much higher density than fully grown trees would be able to thrive, on the assumption that a useful number will actually establish. While trees are mostly efficient at making new trees, that's not useful in areas that are heavily deforested -- and I suspect that's where this kind of technology would be most useful. Dungog in AU (as noted as a trial site in TFA) is a good example (gold rushes were especially bad for local flora, and in hot arid climates it can take centuries to recover). The breathtakingly vast plains west of Beijing that have been deforested, and now result in massive quantities of top soil being blown into the ocean each year would be a fantastic candidate for this kind of mass spray-and-pray planting. Also, when re-foresting, pioneer trees are chosen - typically these are acacias (or similar) that have a relatively short life (10-20) years, are hardy, fast growing, and fix nitrogen. In degenerated older forests you may not find many of these around to produce seed naturally.