The ACO/FiA does in fact use data for determining BoP. The problem is that they have a nasty habit of introducing politics into the equation whenever it suits them. There were enormous marketing/financial gains to be had (by many interested parties) with the revival of the old " Ferrari vs Ford " Le Mans wars, and because the organizers are under constant pressure to "grow" the series, the temptation to "fiddle the books" is just too much.

The problem is that this is profoundly disrespectful to the other competitors and can often even put peoples careers at risk.

Expect to see more of the same "politics" once Peugeot comes on the scene.