I believe that it's a physical plant thing. We have spent over a hundred years building hydrocarbon-based energy infrastructure. Much of that is still out there. Wind and solar have made a ton of progress in the last 15 years or so, but it's only really become substantially better financially in the last 5 or so years maybe. It's still going to take decades to actually replace most of that stuff, just as a matter of how fast we can build and install hardware.

Note also that it's a worldwide chart, so it includes developing countries that may not be so quick to jump on projects that are expensive right now even though they'll save a bunch of money in the long term. Though to be fair, some may have a leapfrog effect when it comes to building brand new infrastructure.

Coal is dirt cheap, to the point where most of the cost is in transporting it and the infrastructure to convert it to power is simple and not very capital intensive to it’s the first thing developing countries reach for when they don’t have strict environmental regulations. It also doesn’t require as much precision manufacturing so a lot can be done domestically even in less developed industries, which is important when foreign currencies are in short supply.

That’s because of the primary energy fallacy: https://medium.com/@jan.rosenow/have-we-been-duped-by-the-pr...

TL;DR: the efficiency of converting fossil energy resources into something useful is poor.