Hi K-Lo,
In all tournaments, yes a hierarchy must exist for chain of command, usually when I am TD, I will have little to do with the actual mechanics of the tournament and/or rulings, simply remaining in a supervisory role for other floors, with them on occasion referring to me for more erroneous situations.
With regard to the hierarchy and the ability to call for another ruling, I have saw it done, but usually it is by the floorperson themselves, who wishes to validate their ruling, I would certainly not normally look to overturn an existing ruling, whether right ot wrong, unless I felt the decision was grossly incorrect. Players can certainly ask for another ruling if they believe it was incorrect, but the first person I am discussing the matter with would be the floorperson who made the decision.
Regards
Stu