To put numbers to it, according to google there's a gravity strength max discrepancy of 0.7% between the places with the lowest and highest gravity on the planet. Assuming using ~17g of beans for a coffee, that comes out to an error of up to 0.12g. Seems kind of dumb to correct for 0.12 grams, in the absolute most extreme case. If they just manufacturer calibrated the machine for "average" gravity then there'd be a max of +-0.35% difference in gravity, for a maximum error of +-0.06g for a 17g brew.