Turn off every other street light in built up areas. There would still be enough light.
But even that relatively small thing is a 'mindset snapshot' that would, like many other things, invariably not stop there. Once it's established that only every other light becomes the norm, it will before long become every other of the remaining lights and so on, until the very idea of street lights becomes an absurdly ostentatious luxury and they all disappear completely.
Then we start to see the same with countless other public costs. Public toilets have been closing up and down the country over the years. Rubbish collections have also been hugely reduced. When I was growing up, your weekly bin collection was just a normal part of life; now it seems absurd to contemplate. Yes, there's the environmental aspect of reducing landfill waste, but the convenient fact that it also saves the authorities a lot of money is mysteriously never mentioned.
Look what happened with student fees: first we had grants; then they were removed and replaced with loans; then tuition fees started, but at a not-too-enormous price; then they rose; then they rose again; now a lot of people will angrily ask why on earth they should have to pay for your university studies that may (or may not) lead to increasing your earning power, and why you shouldn't have a massive debt hanging over you (couched as a considerable 'graduate tax', as if that makes it somehow better) for life?
The state pension will be next: where you'll be considered a disgraceful freeloader for expecting the taxpayer to make provision for your retirement. You'll still have to pay the same amount of tax that ostensibly went towards state pensions during your whole working life, mind.