Believe me an open border would do nothing but increase xenophobia. Canada is dealing with its own immigration crisis with a ton of newcomers DDoSing the overextended healthcare system and real estate market.
Europe has open borders and this hasn't facilitated any increase in xenophobia that I'm aware of, despite many countries having many immigrants.
South Africa by contrast does not have open borders, and is currently going through another bout of violent xenophobia.
I don't think these two things are specifically related.
I don't understand, why have some of the newcomers become builders and doctors?
Canada DoS'd its own healthcare. I'm mostly familiar with Quebec but the overextended healthcare system is mainly our own doing, so is housing shortage.