Do all the big companies listen carefully to small employees and try to develop themselves based on what they hear from them?

Actually there is no generalization to this behavior, it is management methods.
Yet, mostly big companies to have this position them must has clear vision and strategy or they wouldn't be a big company; in such case mostly they involve junior staff in decision making process.
involving them does not mean that they pass the decision, yet they provide their inputs to the management to have clear vision and pass the right decision.

Some are yes, others are not

Big companies are run on policies and rules which becomes the SOP of that organisation which everyone is expected to follow. Anyone going out of the SOP to execute their duties should have a very valid reason while keeping in mind the company's interests. Anyone not falling in the line usually is not seen for long in the organization. With huge work force it is not feasible for HRD to follow on each and every grievances unless it is of very serious nature and has to be managed immediately to ensure company interests are protected

unfortunately no, more the bank or the company get bigger more it will focus on their customers only and spoil its employees