Because their belief in the “pig” thing is a false belief (hell for those that touch anything to do with pork), unless you announce that the money you give them is covered in bacon grease, it would mean nothing. They would not be the wiser and their final destination would be up to GOD … not the bacon grease.
Leaving a ham sandwich in the cab is a great idea, however. Tangible evidence of “pork in the cab”.
What about a "Koran" sandwich with bacon stuffing?