The problem with the changed piece of code is that it would
- both call cp(1) multiple times if multiple *_LIST variables
  were non-empty (which is usually the case), and
- try to evaluate stdout of the called commands as a shell
  script (which would be empty unless someone passed e.g. -v
  to that cp(1) but it's crazy to rely on things like this).

So the functions should prepare arguments for a single copy
command that is predictable and could be made verbose.

Ouch.