Agreed. In Latin America I know of a few PPL's who wear white shirts and bars on the shoulder to be able to get around the airport. Otherwise, makes it difficult.
At my present (Middle Eastern) airline:
1 bar is Second Officer
2 bars is Junior FO
3 bars is Senior FO
4 bars is Captain
The engineers have gold bars overlapping maroon on the normal dark blue epaulettes.
At many other airlines, anything less than 3 bars is cabin crew!
I find that anything less than 3 bars gets confusing to passengers. While deadheading, I've been asked if I am a flight steward, but the J-class passenger didn't ask me for a drink right away.
I find that wearing a big watch helps clarify to those who are not quite sure that I am a pilot.