Polys are under the jurisdiction of MOE, but not owned or
employed by MOE (like all primary and all non-private secondary
schools).
This means that the payslips of all poly staff, lecturers and
tutors are not from MOE (ie. the polys are a private owned
institution), but MOE can issue instructions ("guidelines") to
polys that they must obey, or investigate them if any incident
threatens the reputation of Singapore education system, or else (if
the polys don't obey MOE, they) run afoul of the law.
Singapore govt has (potential) control of everything in Sg, which
is a double-edged sword, with both pros and cons.