Umpiring is a tough job since the decisions that are needed to be made are in real-time. They don't have the privilege of watching the action in slow-mo replays 5-6 times to come to a conclusion. Yet almost all the decisions are correctly made according to the playing conditions.
Then what makes players defer from the umpiring decisions and we see them discussing/arguing with each other. All the umpires that are deployed are highly professional ones and they have trained for years, just like the players, to stand where they are standing. They are trained experts in their fields just like the players are.
Umpires know each and every clause of the playing conditions and they make sure to follow it on each ball. Not many players know all the clauses and that is one of the major reasons why we see them talking to the umpires on most decisions.