[cwt]

This goes for homebrewing (beer/wine) too. If you can make oatmeal you can make beer, but if you want to make the same beer exactly the same over and over it is very complex. The fact that Budweiser tastes the same all over the US and is made in 12(?) different locations is a testament to how good the brewers are (even if beer snobs don't like it).

As for coffee, even the foam on top of an espresso is complex.

You might enjoy this paper if you haven't already read it: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3140933/

[shostack]

This paper contains the phrase "Air–Beverage Interface," definitely going on my reading list. Thanks for sharing!

And agreed on the consistency part. For espresso, once you figure out what you like, you begin the endless quest to make it that way consistently.

[stevekemp]

And baking cakes, bread, pies, etc.