Why does it take so long to erase a drive?

Why does it take so long to erase a drive? I know some software which erase fast!

Overwriting takes a while if we have to go by the standards, especially on slower drives. If erasing with the other program is faster, it either uses fewer overwriting passes or data is never actually written to the disk. So, faster erasing means poor security - instant erasing of even large files usually means no security at all.

However, if you find disk sanitizer to be too slow, you always can select faster overwriting methods with compromising the security.