Before I started flying, that was my imagination as well.
Small Aircraft engines are actually some of the simplest designs you will ever find in a four or six cylinder engine. They are essentially pegged at 1950s to 1970s tech level.
The main difference you will notice first in the controls is that they all still require the operator to manually control fuel mixture. Cars used to be that way too.
But having a carburetor with a manually controlled fuel inlet valve opens the door to the operator getting it wrong and running the engine either too rich or too lean, which can lead to pre-detonation and/or build up of carbon deposits in the cylinders and on the spark plugs. Both of which throw off the engine timing, wear out engine components faster, and can lead to cracking the engine housing, breaking a piston rod, or plain old sudden loss of power during flight when the spark plugs stop working.
And that's on top of the possibility that the venturi can freeze up, starving the engine of fuel and air on decent, even on a hot day outside. Which means the pilot also has to learn to use "carb heat" which is an inefficient solution that sends hot exhaust gas back through the carburetor.
The controls are just two levers, nothing complicated, but the ways one can mess that up are varied. They are also subtle mistakes, right up until you are suddenly losing power at the worst time.
The answer in the car world has been to switch to fuel injectors with computer monitoring and control.
However, even introducing FADEC systems has been a struggle in aviation, LONG after they were well proven in ground vehicles.
As a result, operating just the engine in a small GA plane is harder and more error prone than operating a car engine and the aviation world responds to that increased risk by adding even more regulation around maintenance requirements and overhaul times. Which sounds perfectly rational but there is little data behind the regulations compared to what we could have if most engines were computer controlled and monitored. And we wouldn't need to be so paranoid on maintenance hours if we could rely on issues being noticed before they become problems.
Additionally, this makes flying with those more basic engines a bigger risk because the pilot then has to know the sounds, vibrational patterns, and general "feel" of that particular engine in order to have a good chance at detecting any issues that might lead to a loss of power. But as we humans are well aware from experience making car engines, this is not good enough, there are hundreds of little bits if information that can be indications of the beginnings of an eventual and costly failure that, if noticed early and remedied at the shop, results in continued and more reliable operation.
We start our cars every day and drive to work without really even thinking about the engines. The computers have our backs there. And the vast majority of the time, if anything, the computers are a bit TOO paranoid. But that's a good thing because it means problems get fixed before you end up broke down on the side of the road.
It is even more important that the engine not fail suddenly in flight because then you are forced to land wherever you can, even if that's a farmer's field or a highway. Very dangerous for the people in the plane and somewhat dangerous for people on the ground too.
One would think that the importance of detecting issues BEFORE takeoff and as early as possible during a flight, before the engine actually starts losing power, would make us want to use every tool at our disposal to operate, monitor, and maintain those engines as best as possible. But this is not the case, largely due to the way in which aircraft engine manufacturing and certification are regulated.
I’m inclined to believe that even if the engine components are the same, the whole control mechanism is an order of magnitude more complex than a car.