SF has plenty of those. Marriage and birth rates are low but immigrant populations are high. There are plenty of crowded multi-generational households in SF,

SF has plenty of those. Marriage and birth rates are low but immigrant populations are high. There are plenty of crowded multi-generational households in SF, it's just that they're largely immigrants rather than native-born San Franciscans starting families. (This is also born out in the racial COVID statistics, where infection rates are much higher for Hispanics and lower-income Asians than for whites and high-income Asians.)