The bigger problem is that being a casual package courier is not worth the hassle.

Let’s say someone doesn’t want to pay FedEx $70 to ship a box next-day from San Francisco to Portland, so OP arranges for you to do it and charges $35, takes $10 off the top and pays you $25. Now you are supposed to drive to random person’s house to pick up the package, carry it across state lines, and drop it off at someone else’s house. You have to deal with potential flakes on both sides of this transaction and risk of carrying who knows what the whole time. For $25.

Would you agree to do this job? And if not, would you trust your package with someone who would?