How site can be reachable only through an anonymizer?

There is a site at miamidade.gov.

When I'm trying to access it directly - I am getting a message ERR_CONNECTION_TIMED_OUT. This resource isn't officially blocked in my country, but we have the same situation with different network providers. The site can be reached only through any anonymizer.

How do you think, what are possible reasons of it? Thank you.