What is the idiom for the situation "If people-in-authority don't follow their own set rules then what can one expect from rest of us" [closed]

What is the idiom for a situation that "If people-in-authority don't follow their own set rules, then what can one expect from rest of us" in similar examples given below in different settings:

When HR themselves are tardy, undisciplined then what can you expect from the employees (punctuality and discipline)?

When traffic police themselves are offending (driving without belts, smoking while driving) what can you expect from the vehicle driving community in the city?

When parents themselves are undisciplined (smoking in front of children), what can you expect from the children themselves?

When the management is insincere, what can you expect from their staff?

Do as I say, not as I do

Model yourself after my instructions, not my actions. The phrase implies that the speaker is imperfect and makes mistakes, so one should follow their advice but not imitate them. My dad, a big smoker, always told me not to smoke. "Do as I say, not as I do," he used to say.

Better quote:

Prov. Take my advice, even though I am acting contrary to it. (Sometimes used as an apology for behaving hypocritically.) Jill: Why are you walking on the grass when I told you not to? Jane: But you're walking on the grass. Jill: Do as I say, not as I do.

free dictionary

Generally, in British English, this is always used from either a superior point of view, as a reply to a comment about how the figure of authority is doing something they've told people not to do... Or it's used as a pejorative term from those below the person who is "doing", often with sarcasm:

So it's a case of "Do as I say, not as I do" then is it?

While not an exact fit (because it doesn't necessarily involve figures of authority), what about the following:

If they don't practice what they preach why should we?

from def:

To do the things that you advise other people to do:

He's such a hypocrite! He never practises what he preaches.

(Cambridge)

Also, while not an idiom, hypocrite fits as well.

A “double standard” might be the appropriate term.

a rule or standard of good behaviour that, unfairly, some people are expected to follow or achieve but other people are not:

as in:

• The governor is being accused of (having) double standards in being tough on law and order yet allowing his own cabinet members to escape prosecution for fraud.

(Cambridge Dictionary)

"Lead by example," is a common phrase - often used in management training. The idea is that underlings will emulate the behavior of their perceived superiors in matters of dress and decorum in a particular setting. It worked better in the days before "sensitivity training".

(M-W)