Do unions actually benefit those they represent?

the union im in doesnt do sht for me. we are 150 (strong) in the area i work but we are grouped in with people who live in much lesser cost of living areas. so are wages dont equal sht unless we were to live in those areas with the lower cost of living. my bonus is a measly 600 a year while all the salary people get up to 12%. are voice doesnt mean a thing in our negotiations and we have a no strike clause. it sucks but besides that i love my job. i just hate when they call our wages comparable.