AC has a capacitance/inductance issue in any sort of run where it is surrounded by metal or metallic elements. Usually the runs are short enough and inconsistent enough it doesn’t matter. Metal shielding (required for undersea and most underground) and certain types of soils are pretty much terrible. That said, for ‘short’ runs of less than a couple hundred km, the cost of the HVDC inverter/rectifier drowns out the losses most of the time, so AC still wins most of the time. Sometimes there are still niceties around HVDC (like easier load management) that can still tip the scales.

If it’s a 1000km single run, the math is definitely different, but there aren’t a lot of those. If there are transformers, taps, generators, or other live equipment in the middle, those also change the equation, and in a grid environment, there are a ton of those.