A child has not proven they can be treated as an adult. Like it or not, they really are different.
And any random 40 year old has not proven they can be treated like an adult either. That's a weak excuse.
I would suggest we blame the campaign finance laws that require them to behave that way.
I fail to see the connection between campaign finance laws and politicians pandering to whatever the voters currently want. Election campaigns could magically be free and they would still behave in this manner. They want votes, and consistency (currently) does not win you elections.
... and no principles that consistently direct their decision-making since that would require a spine and would likely interfere with retaining power.
You really want to make excuses for that?
You said it yourself; politicians in the upper levels of government must set aside principles to stay in office. If you want to blame someone, blame the voters who force them to behave that way. We get the government we deserve.
it's funny to watch them read through messages that they've already read just so they don't have to socially interact face to face with someone they really don't know
Have you considered the possibility that they just do this with you?
He who steps on others to reach the top has good balance.