why would sally sell seashells by the seashore when you can just pick them up anyway?

Answer 1

Most of the ones you find are cracked or worn. Maybe Sally goes on the beach after each storm and chooses the finest ones that big waves have just brought in. Or maybe she caters to those who are too lazy to bend down and get their own. She might even label hers as "100% organic shells" and cater to those who think organic is as good as it gets.

Answer 2

Now how do you know that for sure? She could of gotten up early to collect them all and left the crappy ones behind:)

Answer 3

Some people are just too lazy to do it for themselves.