Records of private businesses are private records. They do not have to be shared with genealogists. It does not matter how long your ancestor worked for the company, how much money your ancestor spent at the store, or how “bad” you need whatever information they have.
Private records are just that: private.
Some companies do maintain an archives and are willing to share information with researchers. The records of some defunct companies have been preserved in a public archives. Those are exceptions.
You can try and request information from a company for which your ancestor worked. But they are under no obligation to provide you with any information. 
3 Responses
That’s a new brick wall I don’t know if I’ve encountered yet. What would an issue be? If they were sued or doing something illegal?
Not necessarily. Companies may have employment records if your relative worked there–they don’t have to release those. Funeral homes are also private businesses that may have information on your relative-they don’t have to release anything either. They can if they want to, but since they are private businesses they are under no obligation to do so.
I encountered this when research my wife’s aunt. As a polio victim, She was a patient at a private rehabilitation hospital in St. Louis in the lat 1910’s and early 1920’s. The business ceased to exist in the 1930’s. It was under no obligation to keep any records or to have the records publicly preserved in an archive. Contacting public archives in St. Louis and Missouri produced no records. They simply do not exist. It would be helpful to help date her stay. She left a photo album of her time there and some items about periodic reunions. We have those which my be the most complete record that the rehabilitation hospital ever existed.