The concern, I believe, is that (in the United States, at least,) these orders are a violation of the First Amendment of the Constitution right to peaceably assemble.
The United States was founded on the principles of individual responsibility (i.e. after taking into account the various facts, each person takes the precautions he finds most prudent, and accepts the risks) and accepting that the freedoms guaranteed by the Constitution may also cause hardships, but that the net result of these freedoms is beneficial.
Thus, I believe that the concerns of the original poster are that the various relevant governmental bodies are overstepping these established boundaries in a manner that is unlawful (i.e. in violation of the Constitution) and potentially ultimately detrimental.
Ultimately, the greatest recourse any government has to enforcing its will is violence. Taking into account the events of history, it is reasonable to assume that if these people who are going to playgrounds, beaches, etc. in violation of these apparently unlawful orders resisted arrest, the police would use violence to enforce the will of the government. Allowing this precedent to continue unchecked could be problematic in the event that it be weaponized in the future e.g. by declaring that Catholic assemblies are dangerous due to their beliefs.
As Catholics, we have a responsibility to take care of one another. This is a responsibility that ultimately cannot be abrogated and given entirely to a governmental body. I suspect the topic creator holds a position similar to the following: Those of us who are at low risk of infection should return to functioning in society, taking precautions to avoid spreading the infection. High risk individuals should voluntarily self quarantine as much as they feel is prudent.
