Maybe not an exact law to be greedy but aren't they legally responsible for acting in the interest of the shareholders not the consumer

Not technically a "law"...

"The shareholder wealth maximization doctrine requires public corporations to pursue a single purpose to the exclusion of all others: increase the wealth of shareholders by increasing the value of their shares. However, a company should be committed to enhance shareholder value and comply with all regulations and laws that govern shareholder's rights."

The" however... " part is largely ignored, except for when it benefits shareholders.