"C" = Carbon (basic building block of ANYTHING that has/does/will live)
"C+02" = Stuff plants need (using sunlight the "C" is used & o2 given off
"O2" is stuff humans need but can't actually used without a machine to pump in or "C+O2" (yawning / Lactic Acidosis are 'extreme' end of scale, but "C+O2" is what makes humans suck-wind)
"H2O" = water (evaps off ocean, makes clouds that blow onto land & get rain for drinking water)
"C+O2" = ~ 0.03% if "AIR". "O2" = ~20% & "H" = ~ 90%.
So if one was to conflate / confuse "C" & "C+o2" & "H2O" then one might(?) cause confusion in the population. See how that works? & (they( wanna "TAX" "C" because, ya know.