Their culture reflects the country they came from.
They came from shitty, war-torn countries where education is often frowned upon, religiosity is seen as a good thing, women are treated as objects, sex is seen as the right of a man, etc etc etc.

Their culture is incompatible with ours, which is likely to lead to ghettos being formed, where cop cars are attacked with rocks if they go through.

A lot of them are uneducated, which means we have to educate them in order for them to be of any use.
A lot of them have some form of PTSD, which will either mean they can't work and have to live as parasites for the rest of their lives, or they'll have to be treated. Again, expensive as shit, and they're not contributing anything.

This leads to them being disliked by a large portion of the people already living in the country, which makes them more religious and extreme, and then we have terrorists in a few generations.


So to cap up/tldr:
They rape our women.
Form ghettos.
Drain the economy.
Contribute with nothing (that outweighs the negatives of having them here)

Having worked for several years in some bad parts of Oakland, CA, there is no neighborhood there to which the police will not go. No such thing as a no-go zone for OPD.

I bet if you hask real nicely, they'll even let you ride them!