There are legitimate engineering concerns with structural rammed earth as regards reconciling the desires of environmentalists with the constraints imposed by everything from physics to regulation. Even NAREBA's proposed standards for SRE construction include empirical testing (ASTM's E2392 is similar), because the people who want rammed earth want to use local materials, and soil is obviously different in different places. If you don't know how strong the SRE is, you don't know what you can build with it, so now your architect doesn't know how to change the design until someone builds some local SRE and tests its relevant structural characteristics, which costs time and money. That also doesn't tell you about wear resistance, particularly resistance to moisture, so the longevity of the building is also harder to predict; you can of course point to rammed-earth buildings that have endured for millennia, but you don't see all the ones that didn't, and we know pure SRE doesn't fare well against things like earthquakes and is typically found where certain characteristics of climate and soil converge. So now the inspector, however completely trained, also can't be certain about its structural soundness over time. Reinforcement helps, but in addition to being less sustainable and more expensive and less trendy it's also unknown how the soil will react to the reinforcement, so that's more testing.
This is generally when the same people who think all problems are caused by other people, particularly experts, just not being as clever as they are will rush to suggest how other people's money be spent in sweeping programs to solve the problem -- and, as usual, if we had the will and ability to make those changes we'd also solve a lot of other, more pressing problems.