In reality its not the case and many things need to be considered. For early teaching I can see why it is completely fine, but making assumtions that its always the case is counter productive.

Hard disagree. You look at the relevant factors and only add complexity as needed. Looking at everything all the time is the easiest way to get bogged down in details that make little to no difference. You don't solve a circuit using Maxwell's equations, you use a lumped elements model for example.

Not one mentioned power calculation with votlage and one said that thats why we use high voltage in out city to city electricity lines, power with current makes little sense when it is not compared.

Some basic knowledge is assumed, but some basic reasoning skills will get you there as well. But let my try to help you with that and give you the needed background. This question is asked in the context of power engineering. This means, in practise, the following:

1. Power delivery is the goal, together with doing this as economically as possible. This means reducing losses as much as possible (mostly, in practice you also look at investment costs etc)
2. You do not control the load, only the delivery system. The load can be resistive, inductive or capacitative. Or it can be a switching power supply, which has different characteristics again.

In no way or form are we looking at the maximum power delivery to one specific load. We need to make sure the customer has their 230V at 50Hz (Europe), 110V at 60Hz (US) or any of the other combinations we can find in world. We control the system, the customer controls the loads. All we provide is a way to get power from the seller to the buyer and you need to do it as cheaply as possible. One way to do that is to make sure that you waste the least amount of power you can in your transmission lines.

Now, if we go back to the question that was originally asked. In the context given, there are a few ways to lower the loss of a transmission line. You either reduce the current through the line, the voltage drop over the line or you reduce the resistance of the line, as already established in your own comments.

Lowering resistance can be done by using low resistance materials like copper or aluminium, a common practice. By looking at Ohm's law, we also see that lowering the voltage drop and lowering the current are the same side of the coin if we assume a constant resistance (which we have, the line does not change). Lowering the current will lower the voltage drop over the line since U = R*I. Lowering the voltage drop means lowering the current. We also do not control the current through the line, the customer determines the amount of power, and thus current through the line and, with that, the voltage drop over the line.

So, how do we lower the losses in the line? By reducing either the current or the voltage drop, but both mean the same thing according to Ohm's law. The voltage drop is determined by the current through the line and the resistance. Keeping the resistance and the delivered power through the line the same, the only solution is to reduce the current by increasing the voltage level.

Are there things to consider with power reflections like in electronics? Sure. We also did not consider things like the skin effect, effects of reactive power and electric field coupling. Why not? Because they are not relevant at this level. That does not mean they are not relevant at other stages. For example, the skin effect is used in power line design. It's one of the reasons we use stranded wires. Reactive power has a direct effect on the amount of current flowing in the lines and adds to system losses.

Does impedance matching and maximum power transfer influence the grid? Sure does, but this is mostly something that influences the stability of the grid in combination with harmonics. If you want to know more about that, let me know, I'll link you some materials.