People can make infinite money by breaking and placing the same blocks over and over

This is not a bug. If you want to prevent this infinite money "exploit", make certain blocks have a negative value to place, and positive value to break. This will cause people who break/place the same block over and over again to lose money, or gain money very slowly (depending on what values you choose).

Even if I attached a name to every block on the server, this still wouldn't fix the exploit if a group of people corroborated together. Considering there is a very easy workaround which stops this "exploit", and other methods of tracking blocks would incur a severe sever penalty to implement and still be exploitable, I have no plans to change this behavior.