me_irl

When I was a lot younger, pretty much every washing machine (here in the UK) had both hot and cold fill.

Huh, and I always thought that was a new and shiny thing, never saw it on older (40 yrs+) washing machines when I helped cleaning out houses or something like that. Different countries, different appliances!

than drawing cold water out of the pipework

Yes, that would be inefficient, right. New houses here usually have a hot water ring system with hot water always circulating, so only a meter or so is actual cold water in the pipe, where the connector diverts from that ring. In winter the heat loss from the ring doesn't matter, you're heating the house either way and in summer it doesn't matter because PV and solar thermal bring in so much energy, you can't use it all anyhow anyway.

Personally I have PV so (weather permitting) electric is preferable to gas other than for space heating and bathing.

Same here, PV, battery, heat pump, solar thermal, dynamic pricing electricity and for emergency situations, wood burning water heater and two pumps that runs the whole heating system off the car or a generator using a few watts. When we built the house I opted out of a gas connection, so far that seems like the right direction.

New detergents led to a campaign to encourage washing at 30°C rather than 40-60°C

I've found that some things require a good 75°C from time to time to not start smelling over time. Dog blankets, e.g. - but then again, from April to October hot water is practically free to me, so the temps don't really matter.