tollways vs. Dick Mell

In Critics call for tollway inquiry (Chicago Trib) "an aide to the governor said he had no plans to ask his inspector general to look into the matter."

A few weeks ago when Dick Mell alleged his son-in-law was selling appointments to commissions for campaign contributions, G-Rod invited investigation of the allegations.

But the tollway allegations are different. What makes them different? Would it be that the allegations are easier to prove?