That probably has more to do with who immigrates to Switzerland. I don't now the numbers, but people who immigrate to Switzerland is probably fairly well educated and generally pretty well of.
Denmark is still a fairly high-trust society, not to the level of Switzerland or Japan. We're seeing certain items in supermarkets being locked away or chipped to prevent theft. Now that's not just because of immigrants, Danes steal from the supermarket as well, because prices on many items are increasing rapidly.
Switzerland's population would make it one of the biggest cities in the world, more than double the population of Los Angeles, and more than New York City. Neither of which could be counted as high trust.
The city of LA is just there for administrative purposes. People who live in "Burbank" or "Pasadena" are seen as living in "Los Angeles" by most people outside the region.
You can tell where the city ends very easily. There are well-defined boundaries. Government statistics take that into account. Here's the census page for the city of Los Angeles, which lists a population just under 4 million: https://data.census.gov/profile/Los_Angeles_city,_California...
Denmark is still a fairly high-trust society, not to the level of Switzerland or Japan. We're seeing certain items in supermarkets being locked away or chipped to prevent theft. Now that's not just because of immigrants, Danes steal from the supermarket as well, because prices on many items are increasing rapidly.