The slight flaw with this approach is that it ignores that fact that Irish public servants need to live in Ireland, pay Irish property prices, pay Irish grocery prices, pay Irish petrol prices etc etc. They will be competing in an employment marketplace with Irish private sector organisations.
This approach of exclusively external benchmarking is a charter to tear apart public services by starving it of adequete resources.
As the gov is the biggest employer by far in the state, any reduction in the wages it pays will have a knock on effect on the price of goods and services in the public sector in order for these products to sell. Consequently as prices need to fall, wages, rents etc will fall there also. End result is a more competitive economy which will be able to export. Instead of the government lagging the general economy it is well placed to lead the economy in this regard.