...and that the sort of low-income people who really need this kind of thing cannot be that organised
Fair cop; not everybody is able to respond to pricing signals and thus cut down their costs. So lets have two more examples.
There are services aimed exactly at the sort of disorganized people of which you speak. Like Glowbug. They do pay-as-you-go electricity. They are a lot cheaper than the traditional pre-pay meter from the old-school large electricity companies. You can get a little light-up thing that changes colour and displays your current status, see here: Glowbug: How it works
There is another retailer that gives you a free hour a day of electricity. They have a "fair use" policy, but they actively encourage folks to have do their laundry and run the dishwasher etc in the free hour.
energy companies are not in the business of making losses
All these retailers are in business to make money. The differentiate on many things incluing how much money that want to make, which is mostly about their cost base.
I suspect our electricity industry is structured differently to the UK. The companies that sell electricity to (most) consumers are retailers. Retailers buy electricity at spot price, and sell it for, literally, whatever they want. There are (last I looked) about 27 retailers in New Zealand. Its a competitive space. So different retailers are doing different things, some choose to have shops, others have no physical presence. Some operate through local dairys. (Dairies in New Zealand are like the corner shop in the UK).
Rather than "simply have to put the price up across the board in order to maintain profitability" the unpopular retailers who want to stay in business need to either compete on price, or compete some other way, or they will end up eventually with no customers. There are other parts of the electricity industry, but they are relatively unaffected by this retailer competition.
The smart meter revolution has allowing the consumer to now have a choice, whereas previous it was one rip-off versus another rip-off. This isn't some theoretical clap-trap. This is happening for real.