This would’ve been a non issue if human beings worked together as a species, but we don’t. There is plenty of space on the planet where no one lives and nothing thrives that could be converted massive solar farms that power the planet.
Transmitting that energy from where nobody lives to where people do live becomes the problem with that.
the issue is less the transport distances but changes in "from where to where" sometimes needing some extensions/improvements to the power grid. Through commonly in ways which anyway make sense and all pretty much "standard" solutions well understood. Through there are some more complicated exceptions to that.
EDIT: "distances we speak about" assumed less many local less dense populate/suitable spots across the EU, not a mega project like a energy pipeline from North Afrika.