[bcj]

"They" recommend 60k miles for the plugs mostly to sell more hardware and service.
I put 90k on mine, but only changed them out because I needed a new throw-out bearing around then.

What is usually the weak link is the individual coils that bolt on top of the plugs.
Overheating at the track or idling in the pits is the most common coil killer.
It's not usually a problem driving around, even in the hills.
Those can be replaced fairly easily (sort of, depending on unbolting a few other things).

Changing out plugs can happen too. There's only four of them.
Unbolting a few other things, and a jack, or small hands in situ.

Generally any independent garage can handle it.
Subarus have been a commodity transaction for decades.
I don't have local Portland recs though.