They are so cute and smart! But aren't these containers a little bit small for water or beer?
These ARE small, which is a good observation. Often, model versions of things would be placed in the tomb instead of full sized ones. But they would still function in the same symbolic way (to bring nourishment to the soul).
Similarly, you will see little "shabties" that look like miniature mummies. These were little servants that were placed in the tomb to perform agricultural work in the afterlife. Even though they are usually miniature, they were expected to do the work of grown men!
Got it. Maybe it is a religious tradition that miniatures can be represented as real in a tomb? Or because of limited resources? Why didn't the ancient Egyptians create items as the same size as real?
I think you are correct that in many cases it was a matter of space, resources or money. Egyptian artists were incredibly efficient when it came to design - images tended to be refined down to their most essential parts.