Strange. Traffic tickets are one of the best ways to diverge money from the elite to the poor.
How can any self proclaimed leftist be against it?
There are tons of rich douchebags in California with supercars.
Traffic laws if enforced uniformly would be massively unpopular and get changed. You might be able to get people to bend over and take it like they do in Europe but you'd have to boil the frog for a couple hundred years to get to a state where that's culturally acceptable in the US. Traffic laws enforced discretionarily just become an expensive wheeled version of stop and frisk but with a pretext that makes them constitutional which is not good for society. The status quo of having traffic laws be mostly unenforced except in the case of egregious violations and with occasional spot enforcement is closer to optimal than the jackboot fantasy. Of course there are places where improvement can be made but such opportunity is mostly incremental.
This allows for oppression via selective enforcement and is absolutely a jackboot fantasy.
The solution to the fact that minor civil infractions are potentially ruinous to the poor and that the cops prowl the neighborhoods of the powerless looking for revenue for the state isn't to implement those things everywhere.
Creating a potentially ruinous expense that will occasionally be used to occasionally knock people in the latter group down to the former is anything but progressive and probably not good from a societal POV.