I am like your daughter and never want to put anyone out, however, my husband tells me all the time, not to guess what other people are thinking and don't decide for them. That is, the only way you know if someone is willing to do you a favor is to ask, but don't be offended if they say no.
I personally would pick up a friend anytime of the day or night, because $500 is a lot of money. But you know, another option is to pay for an airport shuttle, which may have only cost $30-$50, and you'd still come out way ahead! That would be for a drop off location about 30 min away, depending on the city. May be something to check out the next time ahead of the trip.