In my field (Engineering) simple graphs are done directly using Latex and packages like PSTricks. Plots are mostly done using Matlab or Python and then exported as vector graphic or if possible as tikzpicture.
Pictures like your provided example are most likely drawn by hand. I mostly use inkscape, which can export the Text in a Latex Format, so all your Text and Symbols corresponds exactly to the ones in the document.
Another possibility is using XFig (www.xfig.org) which is a rather minimal and unhandy vector graphic program. It was widely used at my university to draw mechanical stuff. Has a great Latex support as well.