Actually the Rangers and Astros both have their OTA games on EI. But I have the same problem. I live in Eugene, OR and I am claimed by the Giants and Athletics. That's right...600 miles away, I am claimed by the Bay Area teams, so if they are OTA only or not televising at all, I am SOL. Pretty stupid indeed, and I am under the impression that it will never change.
The MLB 'territories', as many have pointed out, were set in quite literally the dawn of the television age. None want to give up any piece of that real estate, since quite literally it means money in the bank.
In the case of Eugene, OR, I happen to know quite exactly when and why southern Oregon ended up in the SF Bay areas territory. Back in the 50's, when the Giants moved to SF, and quite literally the ONLY broadcast tv station outside of Portland was in Eugene, the big network stations in SF piped their signals north via a private microwave system along the coast up through Crescent City, CA. That system was extended in the mid-50's up through (and past) Coos Bay, OR, and included Roseburg, Medford, and Grants Pass, attaching to VERY early cable systems in those towns.
Remember, there was only ONE broadcast channel out of Eugene, I can't quite remember which network it was, but probably CBS/NBC, and was only 'on the air' a handful of hours each day. I still have picture closeted away somewhere of the VHF antenna arrays on the top of mountains that were required to capture the very weak signal.
So, the analog microwave system bringing in the SF stations operated from that point through the 1960's. Remember, this was WAY before satellite, WAY before fiber. And, when the Giants started the 1958 season, the broadcast areas were defined, and set in stone, at least in the northern areas. And, of course, this was literally decades before MLB expanded to Seattle.
What is interesting, is that not only were the boundaries extended northward, but again (due to microwave transmission of the SF broadcast stations) extended southward as well, to at least the San Luis Obispo area.
As the Dodgers moved to LA the same year, the southern 'dividing line' was a contention for many years; many folks along the southern California Coast became, and are still, Giants fans due to the inroads made by the extension by the SF stations, and many still retain broadcast rights to the Giants games despite the movement of the 'line' several years later.
But again, once an area has been defined, the teams are extremely loathe to give anything up. The teams back east, with the closeness of the cities and the mileage much smaller, means that the broadcast territories are much tighter, and the 'overlap' is much greater.
So where as today, satellite transmission has certainly 'muddied the waters', terrestrial microwave and (especially back east) OTA broadcasting did so in earlier decades. MLB's refusal to address those problems back in the 'early days', means that we live today with a system now 2-3 generations behind in making any sense.
Put into the mix the idea that the owners all have, that restrictive distribution of their 'product' makes it's worth higher, and it's a prescription for (from the outlook of the fans), a disaster. One would think. But virtually all the franchises are raking in the bucks big time with the current system, so any change is pretty remote.