It might be true that repatriation is a costly option, but so are other alternatives. Illegal immigrants are already putting a costly burden on the state by using its resources without giving much back. If this situation is left on its own, the long-term costs of keeping illegal immigrants might be higher than the relative short-term cost of repatriation. Alternatives, such as nationalisation of immigrants are also very costly and time-intensive, and would moreover encourages more potential migrants to come and obtain the country's nationality.