It's important for them to know that the electrical energy doesn't flow like mechanical pressure waves through the water, but in an electric transmission line the energy flows as fields in the space surrounding the wires. This doesn't mean the person needs to understand Maxwell, they just need to know these things called fields exist (in the physical sense) in the very beginning IMO.
page 417, Fig 10-19, found in:
ELECTROMAGNETICS 2nd Ed., John D. Kraus & Keither R. Carver, McGraw-Hill 1973
This one above is interesting, because it shows one place where poynting vector energy flow is a crucial idea: Antenna Design! Kraus' Electromagnetics is essentially an antenna design book aimed at physics students. (But note that Kraus makes an important point: the source in the above diagrams ...is a battery! The propagating EM flow has 0Hz frequency.)