Such prime routes as DTW-AMM on RJ and YYZ-BUD and JFK-BUD on MA. The real problem is the absurd way that OWE ticket revenue is allocated to the airlines, but fixing that would be transparent to the consumer and not affect the fare rules. But OWE revenue is such a small percentage of airline revenue (I doubt it is 0.01%) that the airlines cannot be bothered to address this. The primary impact is the reluctance of some OW airlines to reissue OWE tickets unless they are flying a prime leg.