Other advantages to the tarp vs 2-man tent for non-recreational use is the ability to set up shelter in irregular terrain. A tent needs a specific footprint of clear and fairly flat ground. A tarp will work in a boulder field, urban rubble or a forest of downed trees.
It is also pretty handy in a sudden hail storm or passing squal to just grab out of your pack, drape over you, your pack, your dog and a friend or two.
It is easier to rig your shelter to collect rain water for drinking.
However I don't think I would have survived in Denali Nat'l Park without a bug-proof tent.
leo