To be fair, compliance with that in those cases might be easier. In my experience most washing machines, for example, have programming headers near their main microcontrollers, and you absolutely could write your own firmware for them. Occasionally they’ve been locked down and require an exploit to reprogram (looking at you, Nordic!) but in many cases putting your own code on is as simple as looking up the part number and buying an appropriate JTAG cable. Working out how it’s all connected inside is slightly harder, however.