I don’t know where you are located in California, but Tejon is a rather remote location and it doesn’t surprise me that only 4 stalls were shown as in use when you checked in the car nav. Usage at a Supercharger like Tejon is going to be sporadic, and I5 south of Sacramento and north of LA now has a huge number of Supercharger stalls available: well over 100 I think.
That's partly true, but misses a few key points that make TR crowded. In 2014, when an 85 was the largest battery, and Harris Ranch and Tejon Ranch had no alternatives on I5, People had to stop at HR on the way from the Bay Area, because TR was about 2/3 of the way to LA, meaning too far for the first charge. HR was too far from LA to get there after a 100% charge. And TR had six slots, and a crowd problem. TR was also a spot where two routes merged, so it wasn't just I5 traffic. That pretty much meant that anybody who took the trip used both.
That should all be in the past, and if I go from the Bay Area to LA, I pass about 13 stations these days. But the trip planner is likely to suggest HR and TR anyway. Given that there's no way of adding a charging stop to a planned route, or specifying that one is a long stop (i.e. a meal stop so a person should either charge less at other stops since the car will be there anyway) it means that people will keep getting routed to those two.
For many people, a trip like that is quite rare, and it's not as if they'd learn from experience if they go to Disneyland this year and go to someplace completely different for vacation the next five years on an annual road trip. So it's fair to say that many people will stop there because Tesla tells them to stop there, and they have no reason to think that they shouldn't.
That's especially true if they want to stop at Yogurtland for dessert, even though it's been gone for years, because Tesla still has it on their Web page. I've told them a few times. Maybe if everybody else sends them an email, they'd get to it, but the only people who are affected are the ones who don't go there regularly.
It's not Yogurtland that's the problem, but it stands as a symbol of Tesla being out of date with respect to route planning.