  We study the spin dynamics of carriers due to the Rashba interaction in
semiconductor quantum disks and wells after excitation with light with orbital
angular momentum. We find that although twisted light transfers orbital angular
momentum to the excited carriers and the Rashba interaction conserves their
total angular momentum, the resulting electronic spin dynamics is essentially
the same for excitation with light with orbital angular momentum $l=+|l|$ and
$l=-|l|$. The differences between cases with different values of $|l|$ are due
to the excitation of states with slightly different energies and not to the
different angular momenta per se, and vanish for samples with large radii where
a $k$-space quasi-continuum limit can be established. These findings apply not
only to the Rashba interaction but also to all other envelope-function
approximation spin-orbit Hamiltonians like the Dresselhaus coupling.
