Let us suppose the standard is reduced so that more women can pass selection with the expectation that 50% of the force will be female. Now the force has a requirement for 48 dog handlers. Previously they had 44 men and 4 women. Now they have 20 fewer men.
By definition, there would be 20 men stronger and possessing greater endurance than 20 of the women. In terms of equality they would be penalized. Instead of paying >£15k compensation the force might be liable for £300k. Oops.