Without any actual consequences for getting caught, it's basically a minor inconvenience for the thieves. More officers just means slightly more inconvenience.
Half the people commenting on this post don't understand that railway theft is a federal crime which is handled by federal prosecutors in federal court, and has nothing to do with the "liberal governor" or "lazy California prosecutors".
On nearly anything related to societal matters not of a technological sort, HN commenters tend to demonstrate quite a bit of ignorance of the basic facts of the matter at hand.
Also: obviously you don't just patrol 36,000 miles of track: you patrol where the thefts happen (piles of packaging by the tracks), and on the trains. Since you know the schedule of the trains, you even know when people will be trying to do the robberies...
Consider you may be misinformed.
Very few people (you plus one other) have mentioned that messing with interstate transportation is a federal crime. Which makes me think there is more to this that meets the eye.
Why have the news been focusing on local prosecutors if this is a federal matter? Why haven't federal prosecutors pressing charges?
The trains are in longer segments than ever before with the move to "precision scheduled railroading":
https://www.youtube.com/watch?v=OqdsQ8pFM2s
https://en.wikipedia.org/wiki/Precision_railroading
Sixty-eight thousand American railroad jobs were lost between 2015 and today due to PSR, from a local-maximum* of ~210k in April 2015 to ~142k in December 2021:
https://data.bls.gov/timeseries/CES4348200001?amp%25253bdata...
[*] Down from 2.2 million railroad jobs in 1920, but BLS data only goes back as far as 1947.
Regardless, let's assume Los Angeles was such an economically desolate place for the poor. Well, it turns out that train robberies still aren't a common occurrence in even much poorer places so there must be something else going on too.