How can I find a list of employees at a retailer? For instance, Walmart or Fred meyer?

You can't all employees details are strictly confidential only available to the management and above.

If you know a person who works at the said retailer and they are willing to give you the information off the record, so to speak, then that's the only way,however.. bare in mind that this person would be in serious trouble if found out... a disciplinary at the very least but usually instant dismissal.

If you were employed in the offices of said retailer e.g... payroll,administration,personel... then yes you woud have access to every persons file that is employed by that firm,with the correct security clearrance you could access the files in question.

However, you have been put in a position of honesty and integgrity, therefore you would not access personal details on any other person within the company, only when given permission from higher authority prior to doing so.