It's no surprise this sort of thing would pop up. It's not unlike the problems that arise due to things like car sharing and airbnb, when insurance companies and landlords get involved.
Insurance companies are probably willing to let it slide if you let someone else who's insured drive your car, and landlords generally allow you to have guests. But lending your car to complete strangers, for money, and letting complete strangers stay at your apartment, essentially short-term sublets, are not really what they are prepared to tolerate, at least not without altering the terms and rates they charge for coverage or rent.