Would it surprise anyone to know that BP had already developed the technology to accurately measure troublesome oil and gas flow mixtures at the well head two years ago? It can be done remotely and continuously, at up to 10,000 feet, with a clamp-on, calibration free, sonar flow meter, or that the company that sells and installs them is presenting at petroleum conventions in Calgary and Newfoundland this summer?
The reason BP does not want the true flow known, is that it would require them to pay the "legitimate" fines and royalties they owe on what is extracted, regardless of whether it is ever recovered. As of mid-June their violations of the Clean Water Act alone are around $10B.
The reason no other oil driller wants it known, is that they may own the next blowout and will also want to conceal their true obligations.