There's a clear difference between these resources.

If you could use 100 times more electricity and water at the same cost (with no damage to the environment), would you? We might find uses for doing that, if those resources weren't relatively scarce.

If you give an average consumer a 10tb hard drive, will they use it all? Probably not even close. The amount of storage wasted by consumers is beyond epic, thrown away with the next system upgrade (someone want to count how much storage America has thrown away in the last decade?). That's the bandwidth context. We can keep boosting the amount of bandwidth for an exceptionally long time, at little additional cost over what the present infrastructure cost. You can go from 100mbps to 200mbps while not having to rebuild everything. Try doubling the output of or availability of water or electricity like that.

Put another way, bandwidth - like storage or processing power - is a hyper expanding resource; one in which we can even expand just by being clever while using most of the existing infrastructure. Water and electricity are nothing like that.

Humans could easily consume all the fresh water on this planet. We can expand storage, bandwidth and processing power to such an extent that we can never saturate the total capacity. In fact, in the first world, that has already mostly occurred for consumers with storage and processing power (and for the radical majority of all server side use cases). Will 99.99% of all web sites ever need a 1gbps pipe? Nope, and they also won't need 1tb of storage, or 64gb of ram, or a 16 core modern Xeon processor. Those sites will never have enough content to consume such resources, and certainly not in the next decade.

The waste is less, if you weight storage by performance or energy efficiency. Then, we're throwing away low-yield storage and replacing it with high-octane storage. The 'waste factor' becomes small.

Also consider most discarded storage is a fraction of the size of what it is replaced by. So the fraction of waste is always small (compared to its absolute value).

Right, and that's another way in which bandwidth, storage and processing power as resources have absolutely nothing in common with water or electricity. The ability to waste exponentially greater amounts each generation.

Do I need to watch a late night talk show at 1080 on YouTube instead of 720? No, it has only modest impact on my experience, but I do it anyway because there's no cost associated to doing so. I can freely waste vast amounts of bandwidth (or storage, or processing power) with minimum concern, rather than focusing on conservation.

My phone is another marvel in that regard. It costs $0.50 per year in electricity, about 1% to 2% of what my desktop PC consumes. I can waste my phone's resources freely with very minimum concerns for the environment, especially relative to most other things in my house or life that use electricity.

Water and electricity will never have these properties. It's unlikely the average person will ever be able to waste vast amounts of either without concern.

I'm not sure its meaningful to even talk about 'wasting bandwidth'. The cable is doing something all the time - whether or not your meaningful bits are travelling over the wire. So its imaginary to say 'now the cable is in use' and 'now the cable is being wasted' - its only a different state to a human mind, not to the universe.

At any given moment it is finite, but it is always expandable, and not a consumable resource.

Using more bandwidth helps push the expansion. If we had extremely high rates, and low caps, you'd never get things like video services, and bandwidth providers would never have incentive to expand the network. So the more use the better.

The same could be said for electricity, no? I should leave the lights on all the time to increase energy demand so they build more wind farms and solar plants?

Only if you ignore the consequences of recklessly burning fossil fuels, and are 100% sure wind and solar can replace it. So, no. But to be clear, I didn't say waste bandwidth to drive growth, I said unlimited bandwidth promotes growth of services that use bandwidth.