Let's say you have no idea what cars are. Okay, here's how it is.
We allow individuals to aim large metal containers in wheels along a hard surface. The only guidance is the edge and the middle of this surface. Sometimes there are lines marking these boundaries, other times there are none.
The middle boundary is there because other individuals are aiming their vehicles towards you, in the opposite direction.
Most of the time, especially in areas where people are waking (we'll get to that in a minute) there is nothing to prevent them from driving into your vehicle. Why does this not happen, anyway? Because we trust them not to be stupid. That trust is checked just once, in most cases, as soon as they start driving. This trust is embodied in a document that gives them a licence to drive.
Right next to many roads is an area were people walk. Again, there is often no boundary, except for a small raised area and perhaps a painted line, between the vehicles and the people walking Again, we trust that vehicles will stay on their side of the boundary, and people will stay on theirs.
Fine so far? Why, this is no different to the horse and cart, but for a few details.
First, even at their slowest, vehicles travel at six times the speed of a walking person. At their fastest, they may travel up to fourteen times as fast.
Vehicles approaching each other from opposite directions have a combined speed of between twelve and twetnty-eight times that of a walking person.
Second, vehicles are made from hard materials. Far harder than human flesh.
Third, they are piloted by ordinary people like you and I, who make mistakes, have bad days, lose focus, or get angry.
As a consequence of this, there are many occasions daily, worldwide, when vehicles do not stay within their allotted boundaries and collide with people or other vehicles. This often results in death or serious injury. However, we continue to trust that people will steer well enough to avoid collisions, despite the fact that they are a daily occurrence.
Further, even when they are going in the same direction, we trust their drivers to apply a brake in order to prevent collisions with other vehicles travelling the same way. This trust is also violated on a daily basis, with collisions caused by a failure to apply the brake in time to avoid hitting the car in front.
There is no cooperation between the vehicles travelling in the same direction. They are expected to follow each other. However, some want to go faster and others like to go more slowly. The faster ones are allowed to drive past the slower by pulling out into the opposite side of the road. Again, we trust them to do this only when there is no danger of a collision, although this trust is also violated daily, and collisions between vehicles travelling in opposite directions are especially violent.
Although the vehicles are padded, so that occupants are protected from the impact of collisions, at some speeds the vehicle and, quite often, its occupants are torn apart. There is no protection for those walking along the side of the road.
We are encouraged to travel this way by vehicle manufacturers who promote their brands by making them part of a cultural choice. In order to appeal to as many different people as possible, there are many different types of vehicle that match certain personal identities. Recently, vehicles have grown in size to the point where in some cases they no longer fit between the boundaries determined by the size of vehicles from earlier times.
Although this form of transport can be stressful, dangerous, relatively slow, and uneconomical, change at this point would mean massive upheaval. Almost as much upheaval as the railway did almost two centuries ago.
The 21st century horse and cart is an evolutionary anomaly that is never seriously questioned. Instead, we continue to preserve it against the odds by inventing electric or self-driving cars instead of replacing the entire infrastructure with something safer, quicker and far less costly to maintain.