The Justice of the Peace system was set up
long ago when the population was very sparse. Kind of like circuit riding preachers with religion, JPs gave the public access to the judicial system when there were few qualified judges available.
And, we've all watched a movie or two where a star-crossed young couple wake up the JP to marry them, with his wife & housekeeper serving as the witnesses.
Now why a JP has this level of power in
2023 -- IDK.
imho the system is in place in Arizona law, and it would take legislation to change that law and that just hasn't been a priority.
@AZlawyer may know more, not sure if they are still active?