Well, I don't know about your house, but in my house I don't have hoses with free-flowing sand guaranteed to be right next to my washing machine when I install it. A washing machine that required you to buy sand too would have a hard time in the market; it may be irrational in some sense, but that would be perceived as a huge installation burden by the market and it would not do well.
Excellent points.
Then you need to pay to ship sand. The upside is it would probably be easier to install, downside if it breaks you need to deal with sand.
But it doesn't need to be shipped from the factory in China to the user. Sand can be locally sourced cheaply. Washing machine installers just need an additional material on their truck, in addition to the tools and plumbing supplies they already carry. 25kg of sand costs $0.50 from a landscaping yard.
Somehow, I don't think they ship the concrete blocks from China.
Why not? Concrete is cheap in China and shipping is cheap right now.
Do you have the sand at home? If no, hoards of customers would have to fetch it one by one from some supply, actually causing more environmental damage in sum