There are a lot of papers in which covid19 clusters have been traced to shared living arrangements, sweatshop workplaces, hospitals, cruise ships and other cramped indoor places where people have sustained contact. As far as I'm aware there are literally none of these for parks.

Park shaming is a particularly insidious piece of bullshit that shifts the blame from economic systems that mandate poor housing quality and force people to attend workplaces that aren't adequately distanced, onto people who are doing nothing to spread the virus

(obviously, the people who need the parks are the ones with poor housing and exploitative jobs, who can't just drink G&T in their nice suburban garden while having Zoom meetings on the work laptop, and whinging about the dreadful people failing to distance in the parks)

RT If you want to focus on stuff that's actually causing people to be infected and get ill, focus on the care homes disaster, PPE shortages and enclosed workplaces reopening without adequate protections.The government would prefer you to photoshame small groups having a picnic

This piece is pretty good, on this topic: "of the countries performing contact tracing properly, only a single outbreak has been reported from an outdoor environment (less than 0.3% of traced infections)" https://www.erinbromage.com/post/the-risks-know-them-avoid-them?fbclid=IwAR1JExQ8MY0-ZDLe2y4SQ7K9S9csePTQqJnw2XFnwQ_uMiCsn-5SINt9LGo