Canned beans never, that I'm aware of, have the soaking water discarded.

One of the main points of soaking beans (besides making them cook more evenly and quickly) is to dilute the indigestible oligosaccharides. That's why you toss out the soaking water.

Pre-soaked beans cook up in the pressure cooker in 5 to 15 minutes. Not much is easier (and if you're used to cooking with pre-cooked beans, you can make a big batch and portion it out in the freezer).