Well, most of us who aren't American still fly requently 'internationally', meaning any flight which crosses national boundaries, and often shorter than your 'domestic' flights. So really there isn't much difference if I fly CDG-MUC compared to your examples.

And even though most flights still serve something, I still bring food. There is no telling what will happen before/during/after the flight which may result in a delay. I'm often going places where there is no easy access to room service, nearby dining, or grocery stores. I'd rather ensure that I have something to eat just in case.

The first time you find yourself in an irregular ops situation, ill-prepared, you may change your tune.

But until then, it really can't be that difficult to imagine that not every flight/day goes as planned, can it? Or that many people choose not to eat the mostly unhealthy food found at US airports?