In a case of a gezera or any other issur that might not apply to a particular person (for whatever reason) we often still say it does because of a "lo plog". In order that we shouldn't make differences and exceptions in a gezera that was made or in a case of a particular issur.
What is an example of a "lo plog" from Shas?
What is an example of a case where we should apply the rule of a "lo plog" however we don't?
(I have not provided any examples in my question because that's exactly what I'm looking for a "classic" example that is found in Shas. As well as an example where we find that really we should say "lo plog" but we don't.)