Explain how unions benefited workers and why the owners of a very large business did not like them.

Business people in intense competition with each other to produce a better, less expensive product or service are and always has been good for the economy of any country. When businesses are allowed to become too big to fail, to hire trained gunslingers in the form of expensive lobbyists and contribute heavily to the campaigns of candidates who provide those businesses favors, privileges, subsidies, tax cuts, etc., they cease to be good for the economy of our country.
Business owners hate unions because it gets in the way of them making money.
Unions are hated because they force business owners to do the right thing. Sometimes what is right keeps them from maximizing their profits. There are labor laws, however can be ignored when greed is involved. Most employers get away with it as opposed to employers who have employees with unions.