Lets assume you’re toasting white bread and you want it a little bit toasted - a long way from burnt. Which way do you turn the dial? Towards the black toast picture where the indicator is thickest? Or towards the white toast picture where the indicator is smallest?
It’s not what you’d hoped and you’ve just burned 6 slices of bread.
No optical illusion, it really gets smaller
OK, thinner meaning more power can’t have been intentional. That is indeed very crappy design.
Perhaps the dial was designed and made by a different team or company from the rest of the toaster, and they hadn’t come to a consensus on which way to turn, and they ended up screwing it up, but by the time they noticed they had already mass produced the toasters and dials?