Well the reason is easy to quantify - saving hundreds of dollars a week. In my case, the savings are more substantial because I rent a car almost full time....but I do not use a code with LDW.

The main point of my post was a gentle reminder to everyone that when you rent a car, and do not have your own auto policy, you're basically on the hook liability-wise no matter what - code or no code. The rental company will carry state minimum (if the state requires it), and that might be less than 50k. Credit cards do not provide any liability coverage.

In my case I opted for a non-owners liability policy (just $200 a year) for 100k/300k/50k standard coverage.

In a worse case scenario, using a code with no liability insurance carried by the renter can open both the car rental company and the code owner to a liability claim - and both of these parties will go after the renter to recover any losses and legal fees - this would be a royal mess and certainly more expensive than being without collision coverage and having to buy the rental company a new car in the event of a total/salvage accident.

If you carry your own liability, that is one less big risk to worry about....however no is going to be arrested or charged with a crime for using a discount code, and a rental company has no civil case against a renter for just using a code on a rental as the rental company has made no effort to curtail the use of the code, either by email domain login, keeping the codes off the Internet via refresh or other protective means. They can't sit there passively, read a Internet message board and take no action to protect these codes.