The federal government routinely ties highway funds to conditions like that - they did it with drinking age, as well as BAC percentage for drunk driving laws.
The National Minimum Drinking Age Act of 1984 was [… ] signed into law by President Ronald Reagan on July 17, 1984. The act would punish any state that allowed persons under 21 years to purchase alcoholic beverages by reducing its annual federal highway apportionment by 10 percent.
The federal government routinely ties highway funds to conditions like that - they did it with drinking age, as well as BAC percentage for drunk driving laws.
One example:
https://en.wikipedia.org/wiki/National_Minimum_Drinking_Age_Act
I don’t like that much.