A mounting rail in your trailer or van provides you with solid anchor points to attach ratchet straps to. This should be enough to keep your motorcycle safe, providing you make sure everything is firmly installed.
Also, there are no rules to keep you from using that tie-down bar for other purposes. You undoubtedly use that van or trailer to haul other items too, and nobody wants to be 'that guy', causing a traffic jam due to 'loss of cargo'. That blockage in the Suez might have been started because someone thought attachment rails were superfluous.