If the husband moved away, the wife was still in his home. If he wanted to move his home, he would have to take her with, or give her a get. In his absence, the Beis Din would seize his assets to support his family. The American style of the husband running away and leaving the wife to go on welfare wouldn’t have worked, and the American style of trying to blackmail the wife’s family to pay for a get wouldn’t work since the Beis Din as well.
Relying on an external force to coerce a get raises a shailoh.
An agreement that the husband agrees to support his wife until a get is issued (at a level reflecting the family’s past standard of living or his income, whichever is higher) would easier to enforce than an agreement requiring him to give a get. What is a reputable Beis Din, what is coercion, etc., are tough questions. Money isn’t. And with such a contract, the woman could sue in a civil court under the contract without trying to get the government to collect support which is a much more complicated proceeding. And such agreements avoid all the issues of the various pre-nups.