Unions in Ireland

I think about the way unions impact the lives of everyone who is not a member quite a bit. Over the years the membership of unions in most countries - not just Ireland has shrivelled in the private sector and held fairly in the public sector. Why is this? I think it is because heavy union interference in how a business is run counts as a competitive impediment. The more interference a company's board experience as they try to get things done, the more likely they are to fail. Add up the failures over time and eventually the competition wins. The workers lose their jobs and the business is gone. Maybe to China, maybe to a better run factory down the road, but gone one way or another.
The public sector however is a different matter. They don't compete, are not measured against the market - even if they should be - and generally are impact proof when it comes to what unions can do to a public sector organisation. However in Ireland at the moment money is tight. That is putting it mildly. The constant drip drip of benefits that union members have gained (at the expense of everyone else) has to stop and be reversed. The working life of a teacher is now so light on actual work as to be a part time job with better than full time pay.
We live in a republic. Should we not expect our elected leaders to stand up to the twisting of our arms?