Agreed, and it provides important revenue for transportation projects and helps keep our streets clean so I wouldn't want SFMTA to adjust that focus as-is.
I just wish we had proper (read: higher, accounting for real negative externalities and likelihood of citation) fines for other violations that pose active public safety concerns such that SFMTA would be incentivized to also focus on those and not just the "easy" ones. It would also disincentivize antisocial behavior by repeat offenders.
Why wouldn't it be? It's basically spawn camping or deer baiting or shooting fish in a barrel or whatever analogy you want to use.