Tango is a social phenomenon. The ladies get to walk their new dresses around fancy parties available all week long, the gentlemen get to show off slick moves or silk embraces, there's talk, there's tension and there's feeling.
Now, where you've got society, you've got civilization - and with it a number of rules. Since the dance itself doesn't have too many rules, most of them refer to the relationship with the others, and therefore they apply to the couple rather than its parts. Since the couple itself is asymmetrical as far as responsibility goes, if it messes up, it's the leader's fault. Just like it's the driver's fault when a car crashes.
And the resemblance doesn't stop here.

1. The leader, much like the driver, has a number of tools with which to steer, accelerate or break. Each different car steers, accelerates and breaks in a slightly different manner, and you need to get accustomed to these peculiarities, in order to drive safely.By now, the ladies have probably sneered, understanding that they are being compared to cars. In my own defense, I honestly believe that most cars are smarter then their drivers, at least in what driving is concerned.
2. You drive on the right side of the road. On your right, you should always have the landscape. (In tango, this is true also for the UK).
3. There's traffic. It cannot be avoided. Still, if you are usually more careful not to scratch your car than you are not to lead your lady into a crash, then you should feel bad for a whole minute right now!
4. More crowded traffic doesn't mean a chance for more people to see how great a driver you are. It just limits your freedom to maneuver. Often, it tests your patience.
5. It's more crowded on Friday evening. 
6. There's more than one way to drive a car - and there is a number of conditions which will commonly influence your choice - such as the traffic, the lighting, the driving surface, how tired you are, how much you like your car and how comfortable driving it is, or the music you listen to. Selectively and arguably, all these apply to tango as well.
7. When you reverse, things tend to come at you from behind. So, make sure they aren't close enough to hit you.