PostNL is a private company that used to be government owned. PostNL currently operates at a loss for mail delivery. They are mandated by law to deliver mail and that is something they can't get out of. There is not a maximum what PostNL can ask for stamps but the ACM (Authority Consumer & Market) can step in if they raise prices too much.
So it appears to be privatised but with strict government regulations.
So it appears to be privatised but with strict government regulations.