i had this little realisation a couple of years back, and it keeps on proving applicable to day-to-day life, despite the fact that i rarely play chasings these days.

the chaser's victory condition is: At any one time instant, be at the same location as the quarry.

the quarry's victory condition is: For all instants, be at a different location to the chaser.

the quarry's victory condition imposes its restriction across all instants, so i call it harder.