At times one unit is seen superior when it implements its functions effectively. This makes its functions seen. thus people referring it superior than the others. As you put, none is more superior to the other, except only on the fact that which unit is carrying out its duties effectively. Otherwise, I totally agree that all have equal control powers.
Your analysis is very exhaustive. It is true that a particular control unit may be ineffective to serve the people. Basing on the life examples you have given, it is true that people can impact a control system of a particular unit. This only is applicable when ordinary citizens vote wisely when electing their political leaders. In that case, your vote counts. This will limit the ineffectiveness of the popular control of elected officials. Each control unit has specific roles over bureaucracy. For instance, legislature may not have powers to overrule the president nor the elected officials. It carries its control duties as per the constitution. Likewise, the judiciary is superior by its own in executing its functions. Although the president is the commander in chief of the armed forces, he has to rule within his control limits. This shows that each control unit is superior in its side. However, one may be seen less effective, depending on the measure of power assigned to implement particular duty.