The Republican rally in Oklahoma would be a good example of the type of large scale event that should never have been given government backing under the current circumstances. A very volatile mixture of a large group of people at very close quarters, from many different areas gathered in a metropolitan area, many of whom did not "mask up".
To be fair to those rally-goers, I think if the event were to be held today, the mask-wearing rate would be much higher. At the time I think many of the people attending thought wearing masks was a conspiracy to threaten their liberty, rather than a simple and effective public safety protocol.
The disastrous outbreak in that state might be partly attributable to the rally and the protests that kicked off afterwards. Herman Cain attended the Trump rally without a mask, contracted the virus and unfortunately died a few days ago after battling the virus hard.
The best examples I have seen of how to run a tennis event safely in the current environment have been the WTT exos. They have shown you can run events, and also safely deal with quarantine-breakers effectively during the event. What we are all waiting to see is how a strict structure works for a much more scaled up event like a major.