If one ML solution is better than the other one by only 0.01%, in this context it is worth a lot. It is a winner-take-all type of situation.
Edit: the second point was this: If one ML algorithm gives us a 1% saving and the other one gives us a 0.9% saving, you could say that is a 0.1% improvement or you could say that is a 10% (of 1% saving) solution. A percentage sign without context is not that meaningful.
From what I've seen in several places though is companies tend not to listen to their own people, but are willing to make changes based on the advice of hired "experts". So the experts will come in and ask everyone what the challenges are and what they might do to improve. Then the "experts" will pick several low hanging fruit and find a few things that cross internal boundaries (the harder things to change) and make recommendations. Upper management will go with it and improvements will be made. I suppose the way to sum it up is that they bring objectivity to the table.
that being said, even if ML gets you a 0.5% advantage over spreadsheet math, that is a non-trivial amount of savings on a national scale.