A car sitting 6 feet in the air is also a highly dense storage of energy that could be released at any moment. I do get your point, but there are ways to mitigate the dangers associated with working on a pack, and they're not as volatile as you think. Being exposed to air isn't going to cause a cell to explode as the lithium is mixed with other chemicals inside the cell to make it fairly inert. The danger comes from short circuits, whether it be a puncture or bridging contacts with something conductive.