Most public airports have a variety of types scattered around. The heyday of US light aircraft manufacturing was decades ago and resulted in the production of Cessna, Pipers, Beeches et al in large number. These aircraft are still around but are now aging so the types parked up will often be showing their age. There are light aircraft still being produced today but the numbers are significantly lower. Moreover, they are not cheap so you don’t see so many new planes around. One of the higher end types is the Cirrus. With a nicely equipped example setting you back about half a million dollars, it isn’t a surprise that they are not abundant.
San Carlos, on the other hand, is positively swimming in the things. The peninsula is home to quite a lot of high net worth individuals so this is an area where people are more likely to be able to have a nice shiny Cirrus. Also, there is a distributor on the airfield (no coincidence there!) so the local buyers are likely to choose something they can see at home.
There are some SR20 models in use for training but more seem to be the higher end SR22 models. They are a nice looking plane and one that I would certainly be happy to have a go with. The combination of equipment, control layout and performance would be nice to try and to compare with types I have flown in the past. One day…