"Anil [Kumble] was the one who didn't want that [a pact on trusting the fielder's word] after the Sydney Test for one reason or the other," Ponting said. "To me it's like flogging the dead horse, to tell the truth. I go to every referee meeting before a series wanting to play the game like that, but almost every other captain in the world is not interested."
The catching Law itself has been made problematic by the interference of technology, because as it is framed today, TV technology is unable to clarify anything. Often, apparently clean catches are disallowed after referrals because there is no conclusive evidence. Equally, apparent bump balls cannot clearly be determined to be bump balls. As such, TV replays, even with super slow motion (1000 frames per second) remain unsatisfactory.
The solution is quite simple, and would simply involve a reversion to the old caught law, which stated that no part of the hand below the wrist could be in contact with the ground as the ball made contact with the hand in the process of the catch being taken. This would disallow an entire class of catches where fielders get their "fingers under the ball", often just barely. In addition, the current condition, that no part of the ball can touch the ground until the catch has been completed, should be retained. In such an event an agreement between captains about catches would be tenable, because it would be easy to judge whether or not a given claimed catch was in fact completed. But, as you probably realised while you were reading my previous sentence, this would also render any such agreement to be entirely redundant.
So even if you have two teams who understand the current Law (Law 32) perfectly well, and they trusted each other enough to agree to a catching agreement, you would still have contentious situations when it comes to really low catches. Ricky Ponting exacerbates the problem with his casual interpretation of the Laws, but even if he took things more seriously, and had more control of his instincts and those of his team in the heat of the moment, it would still not guarantee clarity on contentious catches.
It is tempting to suggest that Ricky Ponting ought to introspect about the fact that (by his own admission) no captain in world cricket is willing to enter into a catching agreement with him. But that is a seperate issue and is not going to solve the issue of catches. We can expect some contentious catches irrespective of whether or not there is an agreement. Given the current Law, such an agreement would be ill advised.