The reason floppies have so few tracks (100000 bits per track, only 80 tracks per side!) is that the read-write mechanism didn't track the track. It was just indexed to a specific position by a stepper in the drive mechanism. Because there were a lot of sources of radial position error, and the writing and reading process could be misaligned in opposite directions, the tracks needed to be wide and far apart for reliability, and the erasehead needed to erase a much wider area than what the rwhead could read/write. The various later superfloppy standards that failed to get market traction usually only got slight increases in bit density along the track, and most of their capacity increase from having some way for the rwhead to follow the track, enabling dramatically higher track density. But all those mechanisms would be much more expensive and complicated to do than a simple floppy drive.
But if you use a more precise and expensive machine to write the disk, the normal amount of precision in the drive that is used for reading ought to be sufficient for about twice the track density. The only hw change needed would have been allowing half-step positions for the rwhead, for no cost increase. And I can imagine 80's/90's software devs being interested in a format that is harder to copy at home. Yet no-one ever did it, does anyone know why it was never tried?