Search sites not as cheap as DIY itinerary?

Q. I received an airfare alert recently of a great fare from Houston to Tokyo on Delta for $456 roundtrip including taxes. I live in Dallas, and the fare from here to Tokyo was almost $1000 roundtrip with tax on the very same dates. However, searching further I discovered that on those dates I could fly Dallas to Houston for anywhere between $100 and $200 roundtrip. So doing the math—well, you see where this is going. My question: why didn’t any of the fare search sites I looked at, and I queried about a dozen of them including Travelocity, Kayak, and Orbitz, tell me how I could combine the two fares and save almost $500?

 A. That’s a very good question, and I’m not sure I have an easy answer other than that the software these sites use aren’t equipped to figure out combination fares such as the one you found. Keep in mind that were your flights to and from Dallas delayed or canceled, the airlines wouldn’t have much sympathy for you, and you wouldn’t be able to check any bags through to Tokyo in one transaction (of course, you might argue that even had you bought the single more expensive fare, the airlines wouldn’t have been much help either). If you decide to use this perfectly legal fare strategy, please give yourself plenty (5-6 hours isn’t too much) of time between connecting flights. Another comment I’ll make which will gladden the hearts of any travel agents reading this: good brick-and-mortar travel agents come up with fare savings like this all the time, and I’m sure they too would caution you about the pitfalls.