This is not the case. Most costs are for building and maintaining transmission lines (on all voltage levels), transformer stations and for balance control. The costs of hooking up to the grid are peanuts compared to that.

In Germany the way grid fees are calculated is not set by the utilities*, but by the government. It choose to subsidise energy intensive companies like aluminium melters by exempting them from the grid fee, and thus increasing the fees for normal households and small companies. There is no cost-based rational behind it as you seem to think.

* utilities in the old sense don’t exist anymore because the utility companies have been broken up.

It seems possible to me that much of the costs involved in maintaining a grid is due to individual hookups. It is possible that each location may cost on the order of X euros to maintain a year. Whether the location uses 1kWh or 10,000kWhs. These grid owners may simply be trying to extract X euros to cover X costs per year, with a little markup, and the public may not realize it. So if they charge the household that is consuming only 1kWh a rate of Y and the factory consuming 10,000kWhs a rate of .001Y it could be said they are subsidizing household consumers yet the public sees it in just the opposite way.

There must be a reason why these large utilities are doing what they are. I’d like to get a real understanding.

Since the grid is a natural monopoly, it remains a regulated market. The grid fees are what electricity traders have to pay/charge for using the grid, when selling electricity to customers. How high the grid fees are, depends on which grid level customers tap into the grid.

All grid fee payments feed into a big pile of money that funds the transmission grid, the distripution grid(s), several hundred thousend transformer stations and balancing power plants (system services to keep the grid stable).

A few years ago the government has excempt big consumers from grid fees => increasing the grid fees of the rest of the customers.

Now the EU (AND a German court) crack down on these excemption that can only be seen as special favours too some special interessts. (an industry lobbyist has been very successful )

The excemptions are aditionally questionable, because despite much ado nothing, the grid fees are actually about 20% lower than they were 7 years ago.