Don't forget the Golden Rule!  "S/he Who Has the Gold Rules!" 

 The Feds have the money; the Governors don't. 

Want the money?  Do what the Feds want or forget about their discretionary money.  

55 MPH Speed Limit?  Federal Road Dollars withheld until State compliance.

21-year old Drinking Age?  Federal Road Dollars withheld until State compliance.