One distinction I see is between repair and modification. If you own your car, and the headlight burns out, why shouldn't you be allowed to repair it back to t

One distinction I see is between repair and modification. If you own your car, and the headlight burns out, why shouldn't you be allowed to repair it back to the original factory state? Why should you be forced to pay someone else to do this? If someone tries to argue that you're going to do it wrong, it seems like the onus should be on them to prove that your repair was bad and dangerous.