[Centurion2000]

Have you checked “Faithless Elector” laws?

Show me one elector that has been sent to jail for changing their vote.

Second thing, they can only be punished AFTER they cast their vote. It either is recorded as they voted or voided depending on the state.

Third thing, some of those states use secret ballot for the electors. There's no way in hell you can get a conviction for a faithless elector law in a secret ballot.

[DJ MacWoW]

It may be that none has ever been prosecuted. However, do you believe they will take that chance on not being prosecuted or ruin their political careers?

Also, the SCOTUS upheld the state laws. From the link in post 294.

The Supreme Court has held that the Constitution does not require that electors be completely free to act as they choose and therefore, political parties may extract pledges from electors to vote for the parties' nominees. Some State laws provide that so-called "faithless electors" may be subject to fines or may be disqualified for casting an invalid vote and be replaced by a substitute elector.

Throughout our history as a nation, more than 99 percent of electors have voted as pledged.