Rate the following essay on its writing, argument, and language skills:
Driverless cars are coming, but they may not be the future most people are hoping for. Of course people want one--it is new and cool, but it will not be what they expected. Driverless cars would extremely expensive with all of the technology they are using. Also, it could be very dangerous without an alert driver ready to step in. There are several problems with driverless cars becoming humanity's future.

One problem is money--how will people be able to afford these driverless cars? For example, Google's modified Toyota Prius uses position-estimating sensors, a rotating sensor on the roof, a video camera, four automotive radar sensors, a GPS receiver, and an inertial motion sensor. The combination of all of these is absolutely necessary for the driverless car to have the skill of a human at the wheel. The combination of all of these is also very costly. Only a minority of the population would be able to buy such a car, and just because they're able to, doesn't mean they will be willing to. Many people might think the car isn't worth that much money if they can drive themselves. Economic problems will always be around.

Another issue is the danger of driverless cars. Nowadays, sensors can detect and respond to the danger of out-of-control skids or rollovers and can cause the car to apply brakes by itself. It is a brilliant plan, but what happens when it does not work? Technology cannot always be perfect; it is bound to have glitches at some point. If manufacturers do bring in in-car entertainment and information systems so that the driver will not get bored, that means that the driver will not be alert and ready. For example, if the car's automatic brake system does not work, and the driver is not paying attention, there could be a serious crash with many people getting injured. Technoloy should not be relied upon because there is not a 100 percent guarentee of it always working.

In theory, driverless cars are an excellent idea. However, when they're actually applied and put to use, it is not going to have the best results. Many people may want a driverless car, but how will they get one if they cannot afford it? Not everyone has money just lying around, ready to buy a driverless car that would cost a fortune. In addition, the risk factor is too high. So many things could go wrong which could result in people actually getting injured. Driverless cars may be what humanity wants, but it is definitely not what they need.

Score: 4