"I voted" is like "I gave money to charity" in the "looooook at meeeeee, I'm so good and better than you."
Even better, it's like hanging your HS grad tassle from your rear-view mirror of your Camaro, to show how accomplished you are.
Most people don't need the back pats or recognition for doing right things. Except sychophantic losers with big mouths and bigger egos.