I doubt either of these airlines spends much time or effort worrying about what to charge the handful of people who want to travel between Seattle and Bucharest. I'm sure this is a side effect of the prices of whatever sectors make up this route in either case. Those prices, of course, are based (as discussed above) in part on watching what competitors charge for those flights. The fact that fares on this relatively rare trip came out so close is probably no more than a coincidence. (Even rare coincidences happen. They just happen rarely.)