The manufacturers of the fake solar calculators did not actually say on the packaging they were solar. It is possible the same moldings were used for real solar cells on different models, so they filled in the blanks. Molding cost $$$ even in China, but admittedly they could have used another colour rather than the colour of solar cells, so in that way they are deliberately misleading consumers.
These prices are based upon sweatshop labour. It raises the dilemma - should we buy such products? If we do we are making money for the factory owners and the workers can eke out their existence. If we don't the workers may starve under the facade of communism. Personally, I would not buy cheap arse calculators.