It's because of the screen. Low frame rates are much less impactful on a small screen. When the screen takes up most of your field of view, you notice the frame rate more.
It also depends on the type of game. Quick turns with lower frames an fps shooter will seem very different from low frames in a side scrolling platformer. Third person games often feel smoother with the same frames than with the first person view because the way the game turns is different.
I think a second factor is a lowered expectation of immersion that comes with playing elsewhere. The author specifically says they can play in the pub waiting for friends or on the train or whatever. You're not as invested in those situations, so a game is more of a distraction than an experience.