I feel this might be a bit of a cheeky urban legend, or at the very least a coincidence.
"Main st" has been used in western city's and towns for a lot longer than SF has been around.
It’s a good street, Brent.
(There’s actually good motorcycle parking just off Market I used to use all the time when I worked downtown.)
Here’s an 1853 map https://rumsey.geogarage.com/maps/g3463000.html in which today’s Main Street is only a block long. The map calls it Front St, although there’s another Front St nearby which kept the name – perhaps it was renamed Main to disambiguate once the streets connected?
The other way you can tell that it's not "main" is that it's parallel to 1st Street. Most cities don't have both a Main and a 1st, they have one or the other (which is why "Second Street" is the second-most common street name in the United States behind "Main", with "First" coming in third place). If SF were using Main in the "normal" sense, it would be where 1st is, next to 2nd. Failing that, it would at least be the next block over from 1st, so that 1st was counting from it. Washington, DC, sort of works that way, where there's a "zero street" (North/South Capitol), and then 1st is the next block over. But... SF's Main St. is a full three blocks from 1st. It's just kind of in the middle of nowhere, logically speaking. And that's again because of the landfill situation - 1st St. is the first full block counting from the shoreline at the time the streets were built.
The streets are named Quiet St, John St and Wood St. It is claimed that the naming of these streets is based on the 3 words most regularly used in the clearly passionate council meetings of the time.
The backstory: he was a financial minister and an advocate of austerity, such that when the practice of creating simple, cheap, shadow-profile head portraits of people emerged, his name was applied to them.
https://mountainviewpeople.blogspot.com/2007/09/charles-main...
Here are some more interesting ones...
* Mason jar was named after John Landis Mason, 19th century American tinsmith
* Guppy (fish) was named after Robert John Lechmere Guppy, 19th century British naturalist
* Silhouette was named after Étienne de Silhouette, 18th century French politican
* Bloomers (women's clothing) was named after Amelia Bloomer, 19th century American women's right advocate
* T&T Supermarket (Canadian supermarket chain) was named after Tina and Tiffany, daughters of the founder, Cindy Lee
* Bluetooth was named after Harald Bluetooth, 10th century king of Denmark
Things NOT named after people:
* "Aberration" has nothing to do with Ernst Abbe, optics scientist who wrote about chromatic aberrations. It comes from the Latin root.