Seriously, you ARE kidding, riiight!? Not once EVER has my license been asked for and it wouldn't matter, because it stays in the wallet which never goes into an MP with me. No way.
They're mainly worried about LE -- you should just let them look at it, but not take it (never heard of having to surrender your license). The sign in sheet is bullshit too! Whoever puts down their real name and phone??
Agreed, they worry about LE, so by taken a name and putting on the sheet, they may feel more comfortable...I can only think of one time someone asked for a license...years ago up north, but thats it...never had anyone ask to hold or keep it.