We are often asked why apartments take your driver's license or other identification before you tour an apartment. There are a few reasons why they do this.
First, it's for the safety and security of the leasing agent. In case anything happens, they want to be able to have evidence of who the agent was last with.
Secondly, it is provides proof that the leasing office is complying with fair housing laws. If they take an ID from one person, they have to take it from everyone who walks through the front door, regardless of age, color of skin, or gender.
It's also included in the company policy of most major management companies because it reduces their liability across the board.