That is true but then USA is a Republic where the rule of law matters more than will of the people. The only way people's will can be executed is by first making it a law, at that point all the people who have an interest against the law and unite and put a defense.
However there is a clever trick that the current President has used. Pass laws that are ridiculously long and large. When you pass a law that is 1000 pages long with another 1000 pages of appendixes, no sensible man can read and make sense of it and hence does not have much credible ground to oppose it.
"You think clause 9, subsection B poses a problem for X ? We have taken care of in clause 204 sub-claue 11c when taken into context of Annex. Z" a trick that was mastered by British and Indians.
Ultimately, it is rule of man, since man can change the law.
However you call it, it is ultimately power (of man) that rules other men. Having to push it through the frictional and slow law process merely makes powerful men less powerful by the amount of the systemic friction. But the power gradients still exist and lead to the same consequences.
It merely prolongs a "i dont like him, behead him on the spot" into "i dont like him, make the state attorney accuse him of rape and murder, drag him through courts for 20 years and execute him". But the intimidating effect of power differences is the same. Rule of law is just the same ol rule of man cloaked into law.
In theory it could be rule of machine, if the justice system was composed of some kind of immutable law-enforcing robots, but you're right that in practice rule by law is just roundabout rule by man. Nevertheless, I'd take "dragged through the courts for 20 years" over "beheaded on the spot" any day.