Hi
It is a little difficult to answer the question without having details of your local laws. Also you have not provided the current policy, so it is difficult to say why it will not work.
In india, it is mostly a policy for the company to provide a pair of safety shoes to the workers. That way there is no need to define the shoe. Also in india, in many cases it is done as getting workers to buy expensive safety shoes would be a burden given the salary levels paid to such workers.
In your case, knowing the technical requirement, why should it be a problem for you to select a specific type of shoe and Make it mandatory to use ? There will be technical details available in some study for your industry or in the safety regulation. Why not use the same one ?