Why did business owners resist the growth of unions?

Growth in the number of union members was seen as a threat to business owners because as membership increased, so did the level of influence unions could exert on owners when negotiating conditions of service, wage rates etc. Some enlightened owners recognised that unions could provide a platform for building better relationship's between employer and employee and welcomed responsible workers organisations. Over the decades, their power became too strong resulting in unreasonable and unsustainable demands and in the UK in the 1980's the then Thatcher/Tory government sought to curb the excesses and power of the unions with a good deal of success and they no longer have the power they once held. With the arrival of austerity in the UK however, there are signs of renewed interest in the such movements.