YSK Free shipping over X amount is not a gift to you because you spend that amount, It is a sweet spot that pushes you to purchase an additional item or something more expensive.
from /r/YouShouldKnow
YSK超过X金额的免运费不是因为你花了这个金额而给你的礼物，它是一个甜蜜点，促使你购买额外的物品或更昂贵的东西。