We took over 20K refugees from Balkan in the late 90s early 2000s and not a single fuck was given, nobody even realized they are here. Today most of them speak perfect Czech, pay taxes and hardly any go to mosques. The government can be effective, as long as there is a will to be.
In 2008 - the peak year - alone we had 100K immigrants (mostly workers) come, also, not a single fuck was given, nobody even realized they are here.