When someone says: "Sorry, it's closing time." Does it indicate that he/she works by the clock not by a commitment to customer needs?

When somebody says '' sorry'' Its closing time, it means there is no commitment on the part of that employee. The person is just there for the reward he/she is going to get and not for the interest of the company

Yes..If there is a need of an emergency then it can extend our time as a commitment to our customer service but if possible we must respect the business working hours.

In general, no. 

Sometimes it does, of course.  Sometimes it's just a matter of practicalities, or indeed the law.  Most often I would say it demonstrates a passionate commitment on the part of the employer to not paying overtime.

When he/she says that it is not that he/she is working by the clock and not committed to the customer but following the orders from the above office.