The bottom line is profit.
Eliminating minimum wages, as some advocate, increases the bottom line. Regulations decrease the bottom line, therefore the coal mining industry opposes OSHA regulations that strive to ensure mine worker safety.
Newt Gingrich, a popular Conservative figure on the Right, favors waiving child labor laws so that schools can hire children to carry out janitorial functions (at lower cost).
There is a logic to the bottom line and the ultimate end of that bottom line logic is outlined in the following TED Talk and photo essay: