In the U.S. severance payments are not provided for statutorily, and are rarely made when an employee quits or is fired for cause. However, even when not provided for within contracts it is common to see voluntary severances paid during lay-offs.
Furthermore, in the U.S. it is more likely that they would be "laid off" in order to qualify for unemployment insurance. In Pennsylvania one can make claims on the state-run unemployment insurance system only if one is able to work and does not refuse suitable work when offered. If one quits one is not eligible for these payments.
Ultimately unemployment claims are born by the employer (since their legally-mandated unemployment insurance premiums are adjusted based on realized claims).
So managers with the authority to layoff employees can impose real costs on their companies, both in terms of direct severance payments (which may be optional), and in terms of the inflated unemployment premiums that will hit the company down the road. However, I have never heard of a company attempting to recoup such costs from managers, since such decisions are specifically delegated to managers with hiring/firing authority. It seems much more likely that a manager deemed to have abused the company's purse would be demoted or fired rather than being sued, unless there were some gross fraud involved (e.g., kickbacks).