Public limited companies are run by the public share money by independent promoter
Ref: Under RTI, can account details of a private company be disclosed to a shareholder?
Government is run by the public tax money. Similarly, public invested share holding companies also run by the public share money by independent promotors.
When promotor misuse public share money, they should also come under RTI act as similar to applicable for govt agencies. This is a basic norm which protects public interest. So, RTI must be implemented for public limited companies too.