I did a little lookin' into what happens when you bury a shipping container. The answer is that the sides cave in like a beer can. They are designed to withstand very specific vertical pressures, NOT horizontal weight.
http://www.prepper-resources.com/what-happens-when-you-bury-a-shipping-container-a-cautionary-tale/
https://www.runkleconsulting.com/2014/02/23/no-you-cant-bury-containers/
The sides should be reinforced if they intend to insulate with soil. Otherwise a few temperature changes and rains will fuck the sides up.
BUt they don't have a foundation so it'll be fucked up anyway.
edit: oh yeah I forgot to mention. They're on the West Coast, so Alibaba is a real option for a lot of people and shipping is reasonable. It's conceivable Greta and Co. paid about 3-4k for their shipping container. There are prefab modular housing units with lighting, doors, windows, insulation and basic fixtures for 2-4k. (edit: I WAS WRONG IT'S EVEN CHEAPER
https://www.alibaba.com/product-det...re-Prefabricated-Housing_60761998483.html?s=p They could house more troons in greater comfort for less money if Greta ever bothered to do research and think things through. )
Why didn't they just buy some modular housing from Alibaba?