[micwag]

Most immigration happens between neighboring countries e.g. the biggest immigrant group in Los Angeles are Mexicans.

If you exclude neighboring countries Zurich has a foreign born population share of 27% (compared to 18% of Los Angeles). If you only look at the last 10 years Zurich has foreign born non neighboring immigration of 10% (compared to 4% for Los Angeles).

If you only look at intercontinental migration then Los Angeles wins with 14% (compared to 8% of Zurich).

So yes Zurich is less cosmopolitan then LA, but most of it is just because the US has more diverse neighbors.