Simply that the distance identifier in certain commands breaks the command and just doesn't run it at all.

Setting the following command in a repeating command block it will not kill the fishing bobber

execute as @p run kill @e[type=minecraft:fishing_bobber,distance=..2]

Setting the following command will kill the fishing bobber the tick it spawns.

execute as @p run kill @e[type=minecraft:fishing_bobber]