[turc1656]

If the employee knows that at the time the offer is made, then why would they accept it?

Because it actually is the prevailing market rate for their role and they know that. Also, let's not forget that there is always a large risk when hiring someone, especially as in the OPs case where they are recently graduated. The value can't be certain, so businesses are conservative until it can be proven to be higher. This is logical and expected.

[s73ver_]

But, they don't. And there's also a large risk when taking a job, especially when one is recently graduated.

I'm sorry, but I don't buy this idea that the business, the entity with all the power in the relationship, is entitled to be conservative but no one else is.