The lid safety switch which prevents you from disabling the lid lock. It has a complex design with lots of anti-tamper circuitry. It's highly prone to failure and very expensive to replace compared to the price of the whole machine.
https://www.thewashingmachineproject.org/
That alone will be revolutionary.
Metal work seems very expensive in some places. In a 2025 paper [1], a cooking pot looks like several aluminium rings welded together, about 50 cm tall and 70 cm in diameter, is 416 USD in Ghana, which is one of the destinations of this hand-crank washing machine.
1. https://www.sciencedirect.com/science/article/pii/S266711312...
One more thing, the water is not always easy to get in poor places. It is often much easier to carry laundry to a well, creak, or river than transport water to home. The path to the water sources may be a narrow trail often going up and down hills, so even with wheels on the machine, it is impractical to drag the machine to the water.
What you do is fill it with water. Add soap. Then put in first load of clothes and run it for 15 minutes. Then take out the clothes and put them in a tub. Repeat with second load of clothes in same soapy water. Once, all loads are done, then put in fresh water. Run all loads through it to get the soap out. You are done.
(Relatively) richer people might have another machine that acts as a spinner. Otherwise, you just hang up the wet clothes outside.
The automatic timer part is almost certainly the cheapest part of any washing machine.
Growing up in a developing country in 90s we used to use this type of machine for bigger loads because our normal front loader machine was only 6kg capacity. This + a bathtub was the way to go for washing the blankets, bedsheets etc. It costs now sth like 20-30 usd.
PS: As an example, note the sheet-metal construction. In an industrialized country we would laser-cut all these parts. If you wanted to make this in an area with less infrastructure you might use a template and carbide gas torch to cut out the large shapes, then a hand punch to make the screw holes. More labor intensive, but still doable.