Here's how I look at it: with a Subaru, you know what potential problems and required services you are buying (Headgaskets and timing belt). With other vehicles you don't necessarily know what potential problems you are going to have: some may not have too many major problems but have lots of small ones that will nickel and dime you to death (IE 1996 Jeep Grand Cherokee). As long as you do the timing belt at the proper intervals you won't have a problem there. If your headgasket does go, $1500 buys you the peace of mind that you have another 100,000 trouble free miles on the engine :29:
Yes- this is more or less the impression I got from reading the linked thread: that 100K might be a good average number of miles to figure on a head gasket replacement, and perhaps planing the head(s).
While what you say is true about other brands, not always. Our car (SAAB) is notorious for unpredictably failing in some component of the serpentine belt and its associated pulleys, sheaves, and mountings. Also, in certain years the engine is known as a "sludge monster" unless the correct oil is used, and change intervals strictly adhered to. OTOH, we've been driving SAABs for 40 years. They are now defunct, which is why we're looking at the Outback.
All brands have their quirks, and it's good to know them going in. The VW we're looking at (a diesel) requires a timing belt change at 130K. With belt (and water pump, which also should be changes as a prophylactic measure), that service ain't cheap. There's also VWs "manual/auto" DSG transmission, which requires a service every 40K, and that's at least $400 that most dealers will hit you up.
Let's face it, cars are a money pit, but can be less so with some foreknowledge.