I am only aware of one brand of washing machine that explicitly claims to be designed to be repairable by the end-user--Staber. I have never actually owned or used one before, so I'm not sure how fit for purpose it may be otherwise.
I have successfully repaired other brands of washing machine, dryer, and refrigerator, though. It isn't that difficult, but obtaining the replacement parts is absolutely ridiculous. The first-party site for ordering replacement parts often charges 50-80% of the MSRP of a complete new appliance for just one replacement part.
If any country wanted to encourage repair over replacement, tax incentives are probably not the best way to do it. Publish national standards for appliance form factors, such as case dimensions, screw hole placement, subassembly dimensions, connectors, drive belts, elastic ring sizes, etc. Then phase in requirements that all new appliances must conform to the standard by 20xx.
If all washing machines conform to standard WM-S, WM-M, WM-L, WM-I, or WM-X, and those standards only have three different sizes of drive motor and one kind of power connector and one control connector, then manufacturing third-party replacement motors becomes more economically possible than the current situation, where a Brand X replacement motor might not even fit correctly in two different Brand X models.
The chassis, outer panels, and drum of a washing machine just don't really need to be replaced, unless the paint chips and they rust out. Bearings, seals, motors, belts, control electronics, and knobs, on the other hand, those wear out.
Perhaps I have just been spoiled by ATX standards for computer parts, and connector standards for ISA, PCI, AGP, PCIe, ATA, SATA, SCSI, M.2, and USB. All those standards mean that third-party manufacturers don't have to maintain separate silos for Apple, Dell, HP, Compaq, Tandy, Amstrad, etc. The third-party motherboard manufacturers can just conform to Intel + ATX to sell a product, and maybe also micro-ATX and mini-ITX to cater to small-system builders. It is not difficult at all to assemble a working computer where the CPU + chipset, motherboard, case, power supply, system memory, SSD, hard drive, removable disk drive, graphics card, monitor(s), keyboard, mouse, speakers, wi-fi, and Bluetooth are all made by different companies.
But if you try to replace a single-phase AC 120V 60Hz 5A 0.5hp motor in an appliance with another of a different brand with exactly the same power rating, it probably won't work. The taxes are not the problem--it's getting the parts. As long as the only reliable source of usable replacement parts is the original manufacturer, of course repairing won't be viable. They would much rather sell you an entirely new product!