Think of it from the perspective of the Muslim migrants. They insisted on going to Germany, rather than any other country (except maybe Sweden) because of its generous welfare policies. Human trafficking costs money. Paying migrants to leave provides them with an insurance policy. Even if they don't get in, Germany might cover the expenses of their crime.
And maybe even provide them with a healthy profit depending on the compensation.
Merkel has been flailing her way out of this mess with other versions of this same destructive program.
Her negotiations with Turkey not only made its Islamist tyrant more confident about torturing and imprisoning his political opponents, but it gave him every incentive to view the Muslim migrant spigot as a tool that he could turn on and off in order to be able to get what he wanted out of Germany.
Paying migrants to leave is as bad of an idea as paying Erdogan to keep them out. Both plans attempt to bribe Muslims, outsourcing national security to some outside force.
It can't and won't work.