But Adler had misunderstood the basic nature of the conference. Hoover eschewed federal regulation, preferring to let corporations and state and local governments take action voluntarily; he’d created the conference in this spirit. Even if he’d felt otherwise, no federal law or rule gave Hoover the power to regulate automotive design or highway construction. Adler’s invention required coordination among several levels of government and the car industry. Without an authority to mandate speed governors in automobiles and magnetic plates in roads, the system wouldn’t function. Federal regulations over automobiles and highways wouldn’t become law for another 40 years.
Adler was undeterred. By May 1925, he’d gathered a group of financial backers. On the heels of his successful December 1925 test, he continued to demonstrate the system for journalists, signal makers, police chiefs, state motor-vehicle administrators, and potential investors. He suggested that local authorities could defray the cost of installing the magnets by selling advertising space on the same signs that warned drivers of the danger points. He argued that the installation of speed governors could be made a requirement in annual vehicle inspections. (Source)