If you're 18 or elder you're considered mature enough to pay taxes and even vote. But there’s no car rental company offering car rental under 18 Las Vegas in Nevada, USA.
Sorry, but this is a common age policy of car rental companies all over the world, and you have to accept it.
Car rental under 18 Las Vegas in Nevada, USA users are not eligible to sign a contract and if the renter decided not to pay, it would bring a huge risk to the car rental company.
Besides, any car rental company should be responsible if a car rental under 18 Las Vegas in Nevada, USA driver was damaged in an accident or damaged someone else. So, you won't find a car rental company in the United States or anywhere else which will rent car to a user under 18.