Called to the bar

Practically every car I've owned since the late '80s has had its tyre pressure - both in the handbook and on the sticker on the door pillar/fuel flap - quoted in the metric 'bar' measurement.

So it puzzles me that every time I use the air line at my local filling station the readout has always been switched to the PSI scale. Why? Are people so wedded to the imperial measurement that they painstakingly convert the metric measure? Or do they just stick 30PSI in because that's what their dad used to do?

I switch it to bar each time and leave it that way, but I've never yet found it on metric. It's only a matter of pressing a button so it's no big deal, but I really would like to know why people do it.

GOM