In Australia, and I assume the Netherlands, the transmission network is separately owned and run by government corporations. While multiple private companies are allowed to generate power and sell to customers on the government owned grid.

How does this work? I looked and according to the Internet TenneT is the sole operator of the national electrical grid in the Netherlands. Do you have 52 power lines running to your home?

TenneT runs the what is called the ‘koppelnet’ (linking network). This is a high-voltage network that links the power stations together and also links to the europe-wide electrical high voltage network. Locally, the distribution networks form the link between the high-voltage net and your home. It first goes to a medium-voltage network and finally a low-voltage network. In my case the distribution network is owned by Enexis.

Neither Enexis or TenneT produce power. TenneT is owned by the government, Enexis is a private company but these are heavily regulated (e.g. there are caps on how much profit they are allowed to make).

As a consumer, you pay a fixed amount per day for use of the distribution network. You pay this through your normal energy bill. This is specified separately on the bill. In my case this means I pay €426,95 a year to Enexis. This fee is purely based on the size of my connection to the grid, in my case 3 phase 25 amps. It doesn’t change if I use more or less power.

As for where my electricity comes from? I don’t know, because it changes constantly and with how electricity works, I’m not even sure if this question makes sense. All power producers together keep the grid supplied with enough power. Power stations across the country are linked together and how the generated power is distributed is monitored and adjusted constantly. This also includes capacity from other European countries, as those grids are linked too.

Lots of people have solar panels nowadays and if they produce more than they need they can supply that back to the grid as well and get paid for it (it basically means their electricity meter runs backwards).

What do these companies do if they don't actually produce the electricity or operate the grid?

A bunch of them do produce the electricity, but as I said the power plants are connected to the nation-wide linking network. There is no direct relation between any of these power plants and my home. They can also pay someone else to produce it for them. This could be someone in a completely different country. A bunch is produced locally through solar panels and sold to the power company by consumers.

Some smaller companies may not produce anything themselves and just buy it somewhere, but where als can vary day by day and hour by hour. They will buy it wherever they can get the best deal at that time.

All that matters is that they make sure they provide enough energy to the national grid to cover the use of their customers. How it’s actually distributed is completely separate.

Note that due to how the energy market works, electricity prices change hour by hour. In my case I have a contract with a fixed price for a certain amount of time (1 year, but you can get longer contracts), but it’s also possible as a consumer to get a completely flexible contract. That means the price you pay for electricity changes every hour, based on the actual market price (plus a markup for the energy company of course). Especially during the day when lots of solar power is available, the price can drop a lot. There have even been cases where the price was negative for a short while (i.e. you got paid to use electricity) due to overproduction. If you have a flex contract, your energy company usually has an app that will tell you the current price and the expected price for the next couple of hours.

I have precisely one power company that services about 5 million residents here where I live. No other options.

So if their power plant goes down 5 million people are without power? That sounds extremely fragile.

Hypothetically, what if my electricity, in my shitty profit seeking corporation, cycles inconsistently?

What if my equipment at my rinky-dink substation fluctuates between something absurd like 40hz to 70hz.

This would be extremely dirty electricity\ electromagnetic pollution.

Can be solved by putting a certain quality requirement for putting water into the pipes. Suppliers can compete on price.

It's not realistic to have multiple pipe systems covering the same area. Digging pipes is very expensive. Digging multiple networks of pipes is insane. This solution is the best compromise to have multiple suppliers serve in the same area.