Assuming you don't have indoor plumbing, you need to add more rooms onto your house (or take indoor space away). You also need to plumb both the water supply and the drainage system into your space, which if you're lucky you can already get under your house, and if not requires digging up the floor and foundation. And if you're doing this solo (a la a well and a septic system or similar) you need to acquire the necessary skills (electrical, plumbing, drainage management) and build it all out. I'm not a waste disposal expert, but I suspect the nature of indoor plumbing sending all waste water to the same location makes just running a big pipe to your existing outhouse (assuming you have enough downhill slope) not a good idea. A big hole that can handle the amount of human waste a few people produce is probably would not do great adding a bunch of additional waste water to it every day too.
By comparison, internet can be had with little more than a phone. In fact if you have a wireless phone at all, you probably have internet access, wether or not you intended to get it. And that applies to the homeless people the article mentions too. Let's ignore the fact that a person that is homeless by definition has no home in which to put indoor plumbing, there are also often programs, charities and NGOs providing cell phones and internet connectivity. Basic internet access could be had for $25 / month. I can't think of anything a homeless person could spend $25 on that would secure them indoor plumbing access for a month. Maybe a gym membership? Then again, your internet provider isn't likely to kick you out and call the cops, but a gym might if they catch on that you're just here to shower and use the toilets every day.
I suppose you could take an elevator down multiple floors and then climb into your car to drive to the nearest outhouse any time you need to use the bathroom, but that seems unreasonable to me. So I think in practice "no indoor plumbing" means "a different structure of life", similar to the rural plot of land I spent part of my childhood on with well water, a septic system, and no official fire department or police department. (We had 56k dialup though!)
The point of this article feels like "we've made life without the internet really difficult", which is true, but we use indoor plumbing dozens or hundreds of times a day - washing our hands before handling food, washing our dishes, going to the bathroom, taking a shower, washing clothes, preparing food, having a drink. Its impact on hygiene and general quality of life is hard to overstate and any amount of time spent camping should drive this home I think. The author seems to have actually spent long periods of time without indoor plumbing though, so maybe they just love that lifestyle.
In comparison, sure, the modern person uses the internet a lot, but most of that time is spent doing inessential stuff like browsing social media or sending work emails. If the internet was gone you just wouldn't have those things and you'd go back to, IDK, the radio, newspapers, and typewriters.
Props to the author for keeping Robert's question alive.
That's not what a lack of indoor plumbing is like though. In fact going camping when indoor plumbing exists isn't even the same: when it's a few enthusiasts digging holes sparsely is very different to when the entire population is doing it.
How much of a switch this would be depends a lot on the country: in quite some countries cash is the common method for payment:
> https://www.forex.se/en/travel/forex-index/cash-index/
> https://dailypassport.com/countries-that-still-rely-on-cash/
> https://www.travelex.com.au/travelex-hub/travel-inspiration/...
Though, if we were going to discuss the "disappear suddenly" scenario, losing indoor plumbing seems even more horrifying...
¿Por qué no los dos?
https://thumbs.dreamstime.com/b/man-sits-toilet-bowl-laptop-...