I think public figures expect the public to reach out to them, but everyone is an individual and some people will love the feedback while others may feel it's a burden. I would think that those that are bothered by public attention have found ways to filter it. They may have an employee or publisher who reads it and responds to those that need a response.

I would check to see if they have a website, that should have info on how to contact them. If they are on social media you can reach out to them there or ask what is the best method to send correspondence.