Your EV can modulate its charging very quickly, and "background" loads like electric heating, water heater or even A/C can also be modulated somewhat quickly (though not as quick as an EV's inverter).
The meter needs however to make sure you indeed complied with the demand in order to pay you fairly (otherwise if people can defect on their obligation and still get paid, it defeats the purpose of the scheme of ensuring grid stability).
Doing this at the substation is not granular enough because then you can no longer determine who contributed what and whom to pay, which then removes any incentive for people actually participate.
In theory, this should lead to significant savings and efficiency benefits, as everyone opted into the scheme can now be used as an on-demand load to dump excess power (during which power is not only free, but the consumer may even be paid to consume that power) to smooth out supply/demand fluctuations.
Of course, the UK's smart meter scheme is administered by Capita, so don't expect any of this to actually happen, work reliably or actually lead to any kind of significant benefits, but in theory, it would be a great thing as long as it's done by competent people without corruption/mismatched incentives.
What I describe would be real-time with seconds-level granularity and operated by the grid operator as part of the distribution network and thus provider-agnostic. The idea is to (financially) incentivize people to shift their demand and production around grid fluctuations in real-time - this should allow everyone to get "more" out of the grid by better coordinating supply and production and respond to unexpected events.
If the grid is not stable then it needs upgrades. Automated austerity to cover a backlog of undone work is madness.
This let's me know when electricity is in less demand or high supply and schedule my day around it. Making my electricity bill cheaper and likewise putting less strain on the supplier which reduces their costs too
Paired with a home battery it can be pretty effective, but I don't have one and instead I just work around it and use my electrical heating more when it's cheaper and rely on my insulation to last throughout when it gets more expensive during the day. I've also started cooking dinner later to get past the evening hump.
I'm currently paying wholesale + 0.49 c/kWh margin for my electricity and I'm averaging out to 6.67 c/kWh (incl. margin) in December. Wholesale average has been about 6.61 c/kWh. Add transfer and tax on top of that and it's around 0.13 €/kWh total.
I live in an apartment so the two big electricity-wasters are the dishwasher and the washing machine. Delaying doing the laundry by a couple of days or running the dishwasher half a day later keeps the average much lower. And if you have an EV, just charge it during the night when wholesale prices get closer to 0€.
If you've been on a meter that reads low for a long time, a new meter (mechanical or electronic) will be a big jump.
Any half decent programmer on HN knows what to do when something has almost no chance of happening.
Some of these things display only billable KWH while it isn't so expensive to display current consumption too.
You can also measure it twice so that one can (remotely) see two entirely different readings and replace the meter with one that works properly. It could also display the amount of money owed. (estimate) It would make it slightly more expensive for everyone rather than accidentally billing some people truly crazy amounts.
Just like a bank account can have a configurable limit for withdrawals the smart thing to do is to set a limit per day, week, month and have an alarm go off and/or shut everything down.
Say my monthly bill is 200, I don't want the previous 7 days to exceed 500.
Just a flashing led and a 5000 euro bill isn't smart. Imagine diagnosing a server by how fast the led flashes. Imagine replacing the speedometer in your car with a flashing light. You will know how fast you drove when the fines come in.
Intelligent Octopus Go being one example.
£88 to £143 installation cost in the 2019 analysis. [3:p.21] Smart meter hardware cost £36 to £120 [3:p.22]
£67 to £107 installation cost in the 2016 analysis. [2:p.12] £15 (in home display) + £44 electric + £57 gas + £29 comms equipment costs [2:p.10]
[1] https://assets.publishing.service.gov.uk/media/5a7f59f9ed915...
[2] https://assets.publishing.service.gov.uk/media/5a7f2f8b40f0b...
[3] https://assets.publishing.service.gov.uk/media/5d7f54c4e5274...
Not sure how many years the cost is assumed to be spread over and what the ongoing running costs are but that's the per average customer cost apparently.