> the first user needs the transformer to it's peak size; the second only by the instantaneous-added peak size
Of course, how does the electricity company determine which user was first in this situation. A tariff that depends on the order of connection may not be practical for domestic situations, although it may be OK for very large users, e.g. factories, data-centres.
Using fuse size seems a more reasonable and fair proxy for cost, assuming the same load patterns as the rest of the users. Then again, consumers with EVs might argue that their load pattern is different to the average user (e.g. filling up with off-peak electricity). Also consumers with air conditioning might argue for special treatment given their usage correlates with solar output (except where it does not).
You don't; you let the second one pay more than what the marginal cost was, in order to make the first one not pay so disproportionally.
That only has to happen once there is a second one, though.
Punishing a mere "large enough to not worry about popping it" fuse by billing shared infrastructure based on it (not just billing the stub line from the main in the street to the fuse/meter box in one's home in relation to what wire gauge is needed based on the fuse choosen) is pretty stifling.
If e.g. your furnace fails in the middle of the winter and the repair guy tells you it needs replacing, you might want to get some space heaters and run them for a few days until your actually-wanted new furnace/heatpump/whatever can get delivered, instead of having to get installed whatever the HVAC guy has in the local storage, because if you wait more than on the order of 12 hours, you'll start to get frost damage from pipes and such.
Having to be beholden to an electricity company having time to upgrade your fuses on such short notice so that you can plug in the space heaters without blowing them might be a problem.
But paying say 300 bucks extra because you did that for like 3 days or so would easily be cheaper than the cost of temporarily installing an available loan furnace and then having to remove it again to make way for the actually-wanted one.
They do though bill you if you make them dig the street up to say pull a medium voltage line into your factory that previously just got low voltage from a shared street transformer, but now that you've plans to use a lot more, you'd need the higher feed. Then they bill you and if within like 10 years or so someone else orders service that can piggyback on what capex you paid for, then you'd get a proportional refund from them having to pay off part of your share.
But that's not for just getting normal basic electric service to a normal residential building in a city, that's for building a new farmhouse on the other end of some field where there never was electricity, or for getting unusual service that wouldn't be in the street if you didn't request it.
Merely sizing the transformers/substations to handle the aggregate current of the users attached is not typically handled by the above mechanism, especially because it only covers initial buildout.
Of course, how does the electricity company determine which user was first in this situation. A tariff that depends on the order of connection may not be practical for domestic situations, although it may be OK for very large users, e.g. factories, data-centres.
Using fuse size seems a more reasonable and fair proxy for cost, assuming the same load patterns as the rest of the users. Then again, consumers with EVs might argue that their load pattern is different to the average user (e.g. filling up with off-peak electricity). Also consumers with air conditioning might argue for special treatment given their usage correlates with solar output (except where it does not).