"One problem: I've heard that in some places, when you are a guest and you finish your plate, then it looks like the host didn't give you enough to eat. So some hosts offer very large portions of food; or if you do finish your plate, they immediately put more food on it.
And from what I've heard, these places are not necessarily first-world countries"
Well, there's waste and there's gluttony. I was raised in a culture of food being a central marker of hospitality and family focus where you eating loads of whatever was on offer is a tacit complement to the hosts.. In our background tho, food is normally dished out into serving plates left on the table and dished out by the diner electively - you take what you want and what isn't eaten is left in the serving dishes and so can be recycled into the next nights meal rather than scraped off the plate and put into the bin. So the waste is still effectively minimised.
"About other types of waste: I leave my computer on when I'm at home, even if I am not in front of it. Since my computer takes about 2 minutes to boot, I prefer it that way. Since I have an electricity provider that uses renewable energy, I am ok with it.
About lamps: If the lamps are energy-efficient, leaving them on is not a problem. Unfortunately, energy-saving lamps often takke a long time before they are bright, and LEDs are not always reliable. And constantly turning them on and off is not good for them either.
So just use green electricity, then you don't have a problem."
There are always exceptions and if your behaviour falls into one of the exceptions where the outcome doesn't result in millions of tons of carbon being poured into the environment to power shit that doesn't get used, then all power to you.
That's not what I'm talking about tho. I don't turn my computer off every single time I am away from it either even tho it takes about 10 seconds to boot up. But equally, I do not leave my computer turned on over night when I'm sleeping or if I am going to be away from it for a while because, even tho my computer is relatively low energy (its a surface pro) .. it still about not using power when you don't absolutely need to when reasonable.
These are things I see routinely - and given the Vast majority of power here comes from Coal burning, as opposed to renewables (something like 6% of our power is renewable) - these all add up to an enormous impact on our environment.
People have multiple Computers running in their homes which they turn on and leave on all the time .. they never get turned off regardless of whether someone is using them or not. My kids do this when they stay at my ex's house and it's never policed at all. I turn off the wifi at night and tell the kids to turn their computers off when I decide its time for them to be sleeping ..
People that have TV's in their bedroom that they turn on to go to sleep them leave them on as a kinda all night 200watt night light then can't work out why their electricity bills are so high and isn't it just awful that the government isn't doing something about global warming cos I sure can't be fucked making a minor change to my own personal routine or mindset.
People that leave lights on all over the house in rooms that they aren't using .. Iights, to me are functional purpose based things. If you need enuff light to see details for something you are doing, then turn lights on .. if you are just sitting in a room watching TV - then how much light do you need to do that?.. My entertainment room is about 40 feet long by 15 feet wide. If I am watching TV, I leave two 7w LED lights on that provides well enuff light for me to navigate around the room, see people in it and watch TV .. There are 16 globes available and its pretty routine for me to walk into equivalent rooms where all 16 globes are burning just cos people don't seem to like dimly lit rooms. It's hardly uncommon to go to peoples homes where lights are just left on because at some point - in the day - people were in there and couldn't be fucked turning them off. I have LED in my home and I have no idea what you mean by saying they are not reliable. They are immensely reliable - by an order of magnitude over the halogens they replaced .. they are bright in a couple of seconds, use around 1 eighth of the power and are bright as fuck.
I'm particularly Anal about waste so it annoys me when people use the clothes dryer to dry say a single pair of jeans every couple of days because they aren't organised enuff to do their washing on a routine so that every mornings dress isn't a panic to get clothes dry .. It's winter here now so I can't dry my clothes outside, instead, I hang them inside over a duct so they dry in about 4 hours..
Turning on half empty dishwashers - either wait till you have a full load or wash what you need in the sink, put that back in the dishwasher and wait until you have a full load.
Also - don't buy foods that use an excessive amount of packaging.. They're usually cheaper, you can inspect every single Item you purchase and you don't end up with a bin full of oil converted into plastic that goes straight to landfill.