Car dealerships are not beneficial to the consumer

• Significantly higher markup compared to private sellers.  Expect to pay 30% more, which doesn't sound like a lot.  But essentially, if you spend $15k on a car at a dealership, you get a car you could've gotten for $5k at a dealership.
  
• Dishonesty and ethical concerns.  Pedophiles, murderers and rapists are the only thing preventing car salesmen from being on the lowest-rung of the moral totem pole.
  

• "They provide customer service".  They waste hours of your time: chatting with you, making you wait in the waiting room while they talk to their manager, negotiating prices that they set artificially high, knowing they'll waste your time.  You're paying money to waste 3-5 hours of your time.  They don't help you get a product; they're just a barrier in the way of getting a product
  
• "They can provide knowledge and help you compare cars".   You can find this information online, and get more detailed information (stats, features, reviews, etc).  And there's less potential conflict of interest when learning from an independent party compared to learning from people who are trying to sell you their product.
  
• "They inspect their cars, unlike private sellers".  But there's a chance their inspection wasn't thorough enough.  You always assume that risk.  Either way, you get an independent mechanic to look at the car.   Them inspecting it doesn't change your decision whatsoever.
  

New cars should be direct-to-consumer.  And used cars, just use a private seller.

The two main flaws of dealerships:

• Significantly higher markup compared to private sellers.  Expect to pay 30% more, which doesn't sound like a lot.  But essentially, if you spend $15k on a car at a dealership, you get a car you could've gotten for $5k at a dealership.
  
• Dishonesty and ethical concerns.  Pedophiles, murderers and rapists are the only thing preventing car salesmen from being on the lowest-rung of the moral totem pole.
  

Also, the benefits of car dealerships aren't actually benefits:

• "They provide customer service".  They waste hours of your time: chatting with you, making you wait in the waiting room while they talk to their manager, negotiating prices that they set artificially high, knowing they'll waste your time.  You're paying money to waste 3-5 hours of your time.  They don't help you get a product; they're just a barrier in the way of getting a product
  
• "They can provide knowledge and help you compare cars".   You can find this information online, and get more detailed information (stats, features, reviews, etc).  And there's less potential conflict of interest when learning from an independent party compared to learning from people who are trying to sell you their product.
  
• "They inspect their cars, unlike private sellers".  But there's a chance their inspection wasn't thorough enough.  You always assume that risk.  Either way, you get an independent mechanic to look at the car.   Them inspecting it doesn't change your decision whatsoever.
  

The fact there are so many dealerships and consumers rely on them should be proof they serve consumers well.

-> @Shila

The fact there are so many dealerships and consumers rely on them should be proof they serve consumers well.

No, it's because there is no alternative.  There are laws that prevent companies from selling directly to consumer.  

Because car dealerships lobbied.  They felt that it was unfair that manufacturers could offer a better price to the consumer than third-party dealerships.  Being able to get the same product for a lower price helps the consumer.  This law does not help the consumer.

1. Just because a practice is legal doesn't mean it's ethical.
   
2. Just because something is a law doesn't mean its a good law.
   
3. You still haven't proven why a direct-to-consumer model would be worse for consumers than a dealership.
   

• "They inspect their cars, unlike private sellers".  But there's a chance their inspection wasn't thorough enough.  You always assume that risk.  Either way, you get an independent mechanic to look at the car.   Them inspecting it doesn't change your decision whatsoever.
  

• Dishonesty and ethical concerns.  Pedophiles, murderers and rapists are the only thing preventing car salesmen from being on the lowest-rung of the moral totem pole.
  

• "They can provide knowledge and help you compare cars".   You can find this information online, and get more detailed information (stats, features, reviews, etc).  And there's less potential conflict of interest when learning from an independent party compared to learning from people who are trying to sell you their product.