Bicycles built for long duration use - people do ride for 16-24 hours straight more than you'd think do exist.
And of those people that do, how much do you think they spend on their bikes?
No one who uses a wheelchair does it because they like doing it
Everyone who rides a bike for 16 hours a day does it because they like doing it, and/or they’re an athlete
When you’re done riding your bike for 16 hours a day - likely one week in a year - you can go to the gym, stretch out
The wheelchair guy has to drag himself everywhere
However some of what they are spending money on would make those bikes in Rwanda much better. Better/more comfortable seats can greatly ease the toll on your body. Disk brakes would stop the load much better and so make them safer. A couple gears would be nice (assuming it doesn't compromise drive train strength too much). Modern cargo bikes likely have a better cargo position as well.
Living minimally is a skill that society has essentially turned into a negative trait. Our planet can only support so much, and individual humans are very selfish. There are 8 Billion now.
Is it desirable? Not necessarily. The goal is to be more efficient with water sourcing, distribution, and usage so people have more water to use, not less.