Switch mode power supply is known to be high efficiency. As far as I understand DC-DC convertor has efficiency as high as 98%. I guess the 80% means more than power conversion at home and for the devices. It might cover everything end-to-end including through the grid and step down conversion to either 220VAC or 110VAC. 80% still sounds high to me. Love to hear expert from electric company.
Well, this depends on how broadly they meant it. For example if you include incandescent lighting where most of the energy used is wasted as heat instead of the targeted light, or if you include the energy efficiency of all automobiles, etc., then it might be theoretically OK. But, of course, it has nothing whatsoever to do with the topic at hand, i.e. DC/DC power conversion and its efficiency. Hence, for sure it is marketing hubris.