The practical difficulties aren't really long distance transmission though. They're political and engineering. Spain had a massive blackout recently because a PV farm in the south west developed a timing glitch and they couldn't control the grid frequency - that nearly took out all of Europe and the power wasn't even being transmitted long distance! The level of trust you need to build a giant integrated continent-wide power grid is off the charts and it's not clear it's sustainable over the long run. E.g. the EU threatened to cut Britain's electricity supplies during Brexit as a negotiating tactic and that wasn't even war.
The real question is, why do you expect Space to have fewer political and engineering issues.
The politics on the ground is much harder. Countries own the land, you need lots of permits, electricity generation is in contest with other uses.