I never got a consistent "justice" vibe from the Old Testament. In fact the concept of justice as a series of laws resulting in predictable punishments is hardly how I'd describe how things went. Sometimes God smote people for trivial things (like baking Aaron's son) and sometimes He shrugged off major infractions.
The concept of justice is contradicted constantly. Deuteronomy clearly says that children should not be held responsible for the sins of their fathers but God constantly massacres children with plagues. Even God's beloved David hands Saul's grandkids over to the Philistines for execution because their granddad was a jerk.
What God wanted more than anything was to show that He was the biggest kick-ass God in the universe and his Chosen People were going to be his public relations campaigners.
"Kick the asses of everyone who gets in my way."
That popular quote from Isaiah is just a continuation of the "make straight" quote and is more of God bragging about His gnarly powers than anything about justice.
That's from the New Testament so I don't really know for sure what the parable meant.
I admit the New Testament baffles me even more than the Old.