Public Service Workers: Tipping police officers, firefighters, or other public service workers is not typical and may be considered inappropriate.
Contractors or Repairmen: While offering refreshments or a small gift is appreciated, tipping contractors or repairmen for their services is not standard practice.
Teachers or Educators: Tipping teachers or educators is generally not allowed in many educational institutions and can be seen as bribery.
Postal Workers: Tipping postal workers is prohibited by the United States Postal Service and may be considered inappropriate in other countries.