While I definitely agree that an Earthship is a lot of work (on the project that I was on, we used a hydraulic press for ramming the inner parts... the sledge only finished the tires and still it was pretty intensive labor), I doubt that the Earthbag is as powerfully engineered a structure. And it doesn't take a RPG to figure into it.

That said, I do think that Earthbags are worth looking into, especially when compared to the labor and transport costs involved in Earthships. Unless you have a large flat deck trailer and truck to haul them, there is a large expense to haul the tires, and that's just the start of it. Unless you have a dedicated team of volunteers (as is the case with most Earthship Academy builds), the labor cost is quite high. I do have to disagree about the bags and tires being equally sustainable, but the Earthbag structures themselves are more sustainable, especially when you consider all the concrete needed to make filler 'tires' to deal with corners or end walls. When one considers the massive volume of tires basically degrading to toxins in landfill type sites, however, and to think that we really should be thinking of ways to use them... these could and should be utilized in one way or another... and made inert, by encapsulating them... I'd say that it would be much better for the planet to make some use of them, then mislabeled bags... so I think that's not really accurate.
But are small individual Earthships made of Tires the answer? .............Probably not.
............. Not the way I see it anyway. If the system was in place that made this happen in a way that was easier on the environment (putting the tires on a train (strapped with cables on lumber cars maybe), and taking them, to build something like part of a University campus... or an cooperative apartment complex where the people who were buying into the co-op could partake in the build's labor... and ways were found to greatly minimize concrete use... perhaps with waste steel (which is priced so low right now, it's actually not worth hauling to recycle it)?... then perhaps it might be better to build the Earthships.
As it is, your thread has a great deal of accuracy. Earthships are a ton of work, there is too much concrete, the tires take a lot of energy to transport, and because the tires are best (unfortunately) all of exact uniform sizing for ease of construction, one has to be very selective when getting them, or deal with tons of tires that are never used. Not super awesome in many ways... for smaller projects and maybe alternatives should be found.