Haha yeah Santiago de Chile. Hey I bet you can get a great deal in Santiago de Cuba, way under $100, and it's notable enough people say "which Santiago" like you just did. Cuba has incredibly cheap rent, like Communism works, works mandatory unpaid overtime, in terms of cheap rent.
So those are all beautiful quaint neighborhoods--myself I'm in Lastarria, but come on that's expensive. Yungay, little less. Barrio Brasil, no he cotizado [I haven't seen prices]. Franklin I don't know. I bet Franklin isn't that bad. But uh, try Estación Central. Another place I heard of that sounded like a great idea was Parque Forestal near Baquedano. Huge places at a third the going rate, just because of the violence, which I seek out because it comes with low rent, and which I in particular can handle, as a local. That's my niche. Las Condes/Vitacura is of course much more expensive, because first there's zoning, second it's for GCU--gente como uno[1], they're much more restrictive with buildings than other neighborhoods. Another cheap one is Ñuñoa, practically no zoning, on the subway line and there's tons of huge buildings.
But you gotta be a street cat and adjust expectations. So for instance, there's lots of burglary. All the time. Steal anything, shoes shaver knives children's toys all kinds of shit. Anything. But they're looking for the macbooks. Violence: there's guns these days. It depends on the neighborhood. Bad sentences for armed crooks, like I knew in rehab a guy who put a kitchen knife like between his cheeks but at any rate in his pants for protection when he was partying in the poorer parts of town. He got busted, it looked bad on him, weapons are forbidden. But dude then there's poorer and poorer neighborhoods, cheaper and cheaper rent, it's only a matter of being tough enough for the cheap street. People live in Maipú (pronounced as you fear) for hella cheap.
You just mentioned the neighborhoods where the privileged live. Those are all nice neighborhoods, for the HN crowd, American-friendly (they'll cheat you and steal from you--not from me, but from you--but hell it's cheaper than SF rent). Hell, go live near Pajaritos or Neptuno, I can tell you the rent won't fuck up your checking account. And none of the places I mentioned are tent cities, there's those here too, along with--more common previously--poblaciones callampa, shroomtowns, popping up out of nowhere squatting on unsuited land like shrooms out of the ground, from one day to the next.
It's a mixture of continents. Europe in Sector Oriente, Asia a bit in Patronato (my agent scouted there when he needed Asian actors/models), like there's real Latin American poverty too, but not that that's worse, just poverty is suffering, not a stain on the dignity of the sufferer.
But there's no overlap with San Francisco. The most expensive Santiago place will come in cheaper than the cheapest San Francisco place.
[1] This is a joke indigenous to Chile. They idea is going back not many generations, the people in the target audience for this joke had some money and some status, before downward mobility as the fortunes of the country rose and fell repeatedly. So there's an in-crowd. Specifically, in Chile, one sociological measure of status is whether you have a Spanish surname. So Gutiérrez, Pérez, those are considered--by sociologists, and in general by the culture--low status. Then on the other side is the Basque surnames, with lots of z's and r's, very recognizable, long names. Basques did very well for themselves in Chile, and that's more or less the only thing that matters for status really, is money. Power much less. It has to do with the neoliberal economy, so like the lay of the land up til 2019 was best understood by reading an introductory economics textbook, whereas in America it's the Bible. Money is everything, and like how you go about getting it, where it springs and where it's scarce, and the myriad ways you get fucked when you don't know the trick they're pulling on you. Which you can usually figure out, again with an econ textbook. Gente como uno is like an in-joke of the recent immigrants, not the very recent immigrants from eg Venezuela, but the wave from before which had non-Spanish surnames, like Basque, but also Italian or Dutch or German, or English is good too, Irish is very good in Chile in particular despite the Irish community being vanishingly small (most of it mixed in producing more redheads than blondes, blonde hair is incredibly rare in Chile, to the point any shade of hair that is brown or blonde is called "rubio", which stands for blond/blonde. I got put down as "rubio" in castings, it's a cultural thing, in America I say I have brown hair. It's just blond by American standards, platinum blond, like many Chilean men I know before their hair darkens dramatically (Pedro Pascal being one example, the Mandalorian. I saw an analog picture of him as a child, platinum blond, just darkened dramatically, to jet black, this happens to some Chilean men), so platinum blond, is incredibly rare here, 1 in 10000 people or so. Like if you're a blonde woman interested in Latin men like the bravado the dancing, and sure it's the safest part of Latin America, if you're blonde Chile is not for you, it's considered intimidatingly beautiful, nobody will hit on you. So I'm told.