So a 1980s computer is faster at calculating than a person, so why reduce the cost? Or a car is cheaper to maintain than a horse, why reduce the cost?

Let's flip the script. In reality the averaged transaction _cost_ is probably O(0.1%) or lower. Why are we paying more?

Decision makers and regulators have been bribed in many places.

EU has actually solved this with interchange fees for consumers being 0.3% which to me sound reasonably close to that 0.1%.