They don't have fans in LA.
They spent 1 year in LA when they were first created. Most of those fans are dead or elderly I suspect. their marketing department are making the most of them being an "LA" team originally when in truth they failed there and moved to San Diego to try and get some momentum and fans.
All of their home games are like this in Carson.
Many of their fans from San Diego hate them now and that drive up the 5 is nuts at the best of times.
The Rams own the Stadium they are moving into. They will only rent from the Rams. The NFL though want the Rams to pretend the Chargers are 50/50 owners though.
They still won't fill that stadium. Nor will the Rams for that matter. But the Rams actually have fans from LA.
It's funny listening to friends of mine who support both teams.
The Ram's have more support in LA and will probably do fine though. The Chargers won't unless they win every season.