[U-Boot] bad block handling for NOR flash?

Can anyone help me understand why common/env_nand.c has bad block handling, but common/env_sf.c does not?

env_nand.c writes uboot environment to nand flash and explicitly skips bad blocks. env_sf.c also writes writes uboot environment to flash, but does not have any bad block handling. For my board, env_sf.c is writing to NOR flash over SPI bus.

Is it the case that NAND flash parts have more defects than NOR flash parts, so bad block handling is essential? Or is it just that nobody has gotten around to adding bad block handling to env_sf.c? Something else entirely?

Thanks in advance for any insight.

- Chris