Reporting to the police on missing is a solid proven & employers have no liability to maids at all.
Registered post indicates that the employer has tried all available methods to look for the maid.
According to Lab Law, employers have no right to discontinue a contract without notifying the employee. There was a case that maid sued employer on discrmination while she was admitted into hospital whereas employer believed maid was missing.
Further, this 'missing habit' is one of the maids' +/- agencies' playing games to employers. Employers can stop it by using legally acceptable way. Giving them money just reinforced their lousy behaviours.