1.) The police in Portland were barely interested in dealing with property crime before the massive uptick in 2020. They'd show up...eventually, but they certainly weren't going to show up in time to stop anyone and any investigation was minimal.
2.) The newly elected DA in Portland is a strong believer in restorative justice, and avoiding incarceration when possible. He is also a vocal critic of the police, which has earned him their ire. This has created a circular animosity that manifests in the police not bothering to do their jobs in documenting and investing crimes, because they don't' feel like the DA's office are going to do theirs by prosecuting them.
3.) Judges in Multnomah County, where Portland sits, tend towards light sentencing.
4.) During COVID, the court system effectively shut down for a while. This generated an enormous backlog. The net effect is that there are many people currently awaiting hearings for very serious offenses, who in ordinary times would be in jail, but aren't because of jail capacity issues.
5.) Multnomah County has underbuilt jails for years, and doesn't have much capacity in the ones they haven't closed yet.
6.) Due to COVID, the courts are very reluctant to remand anyone to custody except in the most violent cases. There are numerous reports of violent offenders being immediately released because there's no room in jail while maintaining the recommended COVID guidelines.
7.) Recently Oregon, through a ballot measure, decriminalized user amounts of pretty much all narcotics. The jury's still out on how that's playing out, but it's looking like we may have inadvertently invited a lot of transient drug users to come live here.
8.) There's a massive homeless population in Portland. Almost every neighborhood has one or more encampments. It's not uncommon to see things like stolen and stripped cars, bikes, and other property concentrated around them, because theft is the primary way that these folks have made money.
9.) There's been a massive uptick in meth use across the western United States, which is going under reported because of the opioid crisis. The meth in question is industrially made in Mexico, using P2P as the base. This particular formulation of meth has a very different effect on users than previous formulations (which were based on ephidrine). Ephidrine based meth tends to make people euphoric and sociable, while P2P based meth tends to make people paranoid and aggressive, and in higher doses it mimics the symptoms of schizophrenia. Sam Quinones' new book "The Least of Us" goes into fascinating detail about all this.
10.) Oregon has an awful mental health system, which is way overburdened. The net effect of this is that a lot of people with behavioral problems end up on the street, where they co-mingle with the rest of the homeless population.
11.) There's been an enormous uptick in shootings in Portland, owing to a gang war between the West Side 18th Street, the Young Come Ups, and a few others. There was an inciting incident earlier in the summer where a member of one gang killed members of another at a memorial service, and it's been an escalating series of gun battles ever since. This has seriously overtaxed the police, to the point that in some shootings, one office has been left to process the scene entirely alone because the rest had to go to another shooting.
11.) Police are quitting, for various reasons that range from mask mandates to anger and solidarity that the DA prosecuted one of their own for use of force during the 2020 riots. Portland already had a very low per-capita number of police to begin with.
12.) Until about June, there were two or three activist gatherings per week, and at least one of these usually turned into a small group of people either directly antagonizing the police at their headquarters, or marching around smashing windows and setting dumpster fires. This, too, kept the police very busy.
13.) The culture in Portland forgives a lot of anti-authority things. Theft is excused is "survival crimes". Vandalism is tolerated and sometimes praised, especially if it's enacted against larger corporate businesses. You'll get no pushback for saying "All cops are bastards" to a random stranger in public.
14.) There is an activist culture here that will fight City Hall tooth and nail on any attempt at remediating anything. Attempts to clean up homeless camps are met with protests, sometimes by armed activists. An entire city block was occupied by armed protestors for a month or so last December.
So, in summary, burnt out/jaded cops, relatively soft on crime judicial system stretched to it's max, homeless crisis, meth crisis, fentanyl crisis, general culture of disrespect for authority.
Not sure how much of this is true in San Francisco, but I think a lot of them are generally true across the larger West Coast cities.