Subaru service

I took my 2018 OB Touring 3.6R in for an oil change and tire rotation. Two things I notice (or maybe three): 1. that little engine takes *eight* quarts of oil but regular service doesn't call for synthetic; 2. tire rotation does not mean re-setting the TPMS in each tire to tell it its new location because, through some magic I don't comprehend, the system learns where each tire is; and the optional 3. no mechanic repairing, changing or rotating tires has *ever* managed to set the tire pressure to where it belongs.

On tire pressure, why is it that the recommendation is that it be set cold but does that mean -40F in North Dakota in January or +120F in Phoenix in July? Watching the TPMS readout it is clear that the pressure varies all over the place with the slightest provocation even down to rising on the sunny side of the car.