First of all, many countries, including Italy, are literally installing lagers in other countries (in Italy’s case Albania) to “take care” of illegal migrants, so they are not easily sent back.

Second, the place they come from could well be akin to a death camp for them.

Third, rules like those can be subtly change in a minute to acquire ever more vicious features.

Fourth, as Zexks said, things could escalate once those countries serving their xenophobic policies start caring about the internal externalities of such deals.