Because Tesla was right and Edison was wrong.
No. Tesla wanted to deliver tbrough the air. That’s *only* possible with AC. If you want to understand the Tesla vs. Edison arguments you have to see what Tesla and Edison actually said, not someone writing a book making ridiculous claims to sell the book says.
If your question is why AC instead of DC, that’s one question. If it’s why am I paying for 220V when I use almost only 12V or 5V that is another question, but related.
Let me answer *that* one first. Because whether it’s AC or DC the absolutely undeniable fact is that the amount of energy lost in the transmission line is proportional to the amount of current in the line. Send 100A down the line and you’re losing energy much faster than if you send 1A down the line. But the same relationship doesn’t hold for voltage.
So if you’re energy needs are 100 Joules (1V at 1A for 1second = 1J) they can send it to you at 1V and 100A or they can send it to you at 100V and 1A. If either arrives at your house the total energy is 100 J. But if they sent it at 1V the energy *losses* along the way would have been massively *higher*. They have to charge you for how much they have to send you, not how much you get, so how do you want it sent? The answer (within my example) is 100V at 1A if you want you bill to be lower.
Now, what they *really* do it send it at the highest voltage they possibly can (to get the current, amps, to as low as possible) for as far as they can to reduce losses. That’s the huge transmission towers. Then at some point not *too* far away from you they step that voltage down quite a bit to a few thousand volts to distribute between neighborhoods, then transformers take it down to 220V in the neighborhood to send into houses.
That’s why it ends up in your house as you describe.
Now, the other question... transforming between voltages for AC is easy, cheap, and highly efficient. THAT’S why we use AC for energy transmission. Transforming voltages from AC to DC is inefficient and transforming voltages from DC to another DC voltage is even more inefficient yet.
That’s why AC.
And as far as Tesla goes, transmitting power through the air requires *way* higher frequencies (radio) and is *way* less efficient. Tesla thought we could have essentially infinite power generation so assumed it didn’t matter. He was wrong. And for everyone bitching about cell tower radiation, that’s how you’d be getting your power - but at way,way, way higher powers if Tesla got his way.
Tesla was just wrong. Let it go.