Designing logos can be very difficult. When designing a logo you want it to stand out from the crowd yet still be really simple. Sometimes the designer is really clever and makes the logo very simple yet includes a hidden message within the logo that has deeper meaning.
The Amazon logo is an extremely simple logo and while the arrow may just look like a smile it actually points from a to z. This represents that Amazon sell everything from a to z and the smile on the customers face when they bought a product.