I have an iPhone.I go to places where free wifi is used. Not for...

I have an iPhone.

I go to places where free wifi is used. Not for very long - the length of a train trip, say. Or drinking a coffee.

I use my iPhone internet because - because it's there. It's set up, and I don't need to stuff around. And no ads.

Why would I bother using the free wifi? What's the benefit to me? I'm not talking for a serious downloading session or multiple hours, but for the length of time it takes to go on a train. Why wouldn't I save myself the hassle and just use the iPhone's internet (which is set up and reading to go without me doing anything other than loading up Safari).

I don't understand...?