Tapes and HDDs are magnetic. Flash and DRAM is electric. It is easier to create magnetically stable structures (magnets) than non-leaking capacitors. Flash has

Tapes and HDDs are magnetic. Flash and DRAM is electric. It is easier to create magnetically stable structures (magnets) than non-leaking capacitors. Flash has a better insulator than DRAM, but it wears out with use and leaks more with higher temperature, densities, less margin with more bits per cell...