The window structure is UPVC, in the UK there's no boxing trim around the windows (unless it's a victorian or even older house). Above the bay in the library there's a massive sheet of plastic replacing what was, presumbably, once wood. Whilst our windowsill (inside) is wood, I've seen plastic ones. Our baseboards are wooden tho' - in fact, all except the strip of MDF* that I stuck in because the original splintered to bits when they were removing it from the kitchen are original 1930s wood which is much nicer, and much tougher than modern architraves seem to be.

* Whilst I concur on the whole 'MDF is hideous stuff' concept, the price difference between MDF and the proper wood ones was vast - and this stuff is fairly tough (high density) MDF, so it doesn't dent if you knock it.