[account42]

> What if there isn’t a good plan in place for making people integrate with the local culture and you end up with large groups of people whose beliefs and behaviour are incompatible with those of the local population, e.g. calls for religious rule in an otherwise democratic country and increased violence? Not the blown out of proportion election claims in the US, but rather the real question of what happens to people after they cross the border? If that detail is unaddressed then people might grow to desire more closed borders, even if the issues lie elsewhere.

Integration is primarily a numbers game. Most people don't integrate into the local culture unless they are cut off from their own. If you have so many immigrants that you either need to build immigrant housing or fill up entire towns with them then you don't get immigrans assimilating into the local culture but rather them bringing their own culture no matter what other measueres are implemented. So yes, a good implementation of immigration needs closed borders at least for foreign cultures - these things are not independent.