Most all manufacturers require warranty work to be performed at the factory. If the issue is something simple, most manufacturers will authorize the repair to be done in your local area.
If the issue is more serious, most likely they will want you to bring it back to the factory.
The reason for this can be blamed on trailer owners who falsify a warranty problem. It is very common for unethical trailer owners to not disclose that the damage was caused by an accident or some other non-warranty incident.
Some consumers will provide fake or inflated repair estimates for problems that are not warranty related.
In addition, most dealers are not equipped for any repair work.
It is important that you read your warranty document carefully and make sure to follow the procedures closely if you need to file a claim.