why generation

The generation numbers are multiples of the basic excitation voltage for that design. Using series or parallel combinations you can obtain those voltages at various current levels.

Re: Transmission

The basic rule of thumb is that the larger the current, the larger the cable that is required. So if you send large amounts of power at much higher voltages you can use thinner wires (smaller cables). Also because power loss is primarily a function of I*I*R it makes sense to transmit at the highest reasonable voltage. Of course, special equipment becomes necessary to handle it.

For no reason at all.

The generation gap is however more serious.

Has anyone counted the number of 11kv steps questions per month?

Are we talking about My Generation

No stutter needed

form factor

Everything started (over 100 years ago) with 100 V

Than engineers found: we need extra 10% for voltage drop > got 110 V

Then another 5% > 120V

Now to generate power over MW and have fair size of conductor (higher current -kiloAmperes => & higher kA > thicker conductors!) so 10-11 kV came for generator insulation. And because of this insulation limitation generated voltage of 11 kV w/ transformer ratio 10:1 transmission lines becomes 110 kV. > 220 kV etc for transmission linesw - long distances, drop voltage more significant. Three phase in EU moved 220 * 1.73 (sq root of 3) to 380 or 400 kV with extra 5%.

USA did not care what was going on in EU and have popular 13.8 kV 138 kV etc, for their transmission lines. This is a very simplified explanation. Maybe too simple.