That is a massive oversimplification. There are a huge number of variables that have a very noticeable impact on the coffee. Pressure (over time), temperature (over time), flow rate, composition of the water, puck resistance (and change over time), many ways to change how the water extracts from the puck, pre-infusion time (and temp. and pressure...). This is just the machine side, ignoring beans, grinding, distribution and tamping.

And the effect of a single one of those variables can be the difference between a god shot and something that tastes rather off. I am not saying you need a machine that allows you to control all of this to get good shots, but the effect on the result is still there. Something like a Decent DE1 can actually control a lot of this, a lever machine actually allows a lot of control as well. 100$ pump machine to an expensive espresso machine is a huge difference in many regards. Consistency being probably the biggest one.

So no, I do not thing your assessment on complexity of espresso making is an accurate representation. I concede however, that if you know what you are doing, good espresso can be had on cheap-ish machines, it's just much harder and less consistent.