Tipping works because most people are "sheep"

What do I mean by "sheep"? It means they just follow the people and systems around them without critically thinking for themselves.

Oh the ice cream joint asks for tip at the checkout? Must be normal. Tip.

Oh the restaurant terminal starts tipping at 20% instead of 10%. That means 20% is normal so let me tip 20% or 25% cause I don't want to give the minimum.