Model releases are only required for advertising or similar commercial uses, and sometimes, may not even be required for these. Editorial use (travel guides, books, posters, postcards, calendars, websites, encyclopedias, newspapers, magazines, textbooks) does not require any model release or property release as long as the activity shown took place in public, and was photographed from a public place. The TV crews were filming these events, and of course they do not even try to get the usual releases from people; it is treated as 'news' because it is public. Some stage performances, concerts, pageants etc are public too.
I do not sell pictures with people in as Royalty Free, and on Alamy, this restricts the value. RF pictures sell for much higher fees. My daughter sold a picture of an empty beach - no people on it - for $390 this week, but my average Licensed editorial sale is around $100. You are not allowed to list any image with people or property in as RF, unless you have releases for everyone and everything shown. But you can list almost anything as L (Rights Managed) with a release. It is up to the buyer to decide whether their use is likely to cause legal problems, having an unreleased image published. The photographer is not responsible, nor the agency. The legal action would be taken against the buyer/user, and if they can see it has no release, it is their decision.
If you take pictures of people in their own private space - in their gardens, in a club or venue where a ticket admission has been paid, inside the compound of a public swimming pool where admission is paid, in hotel grounds where they are paying guests, in a restaurant, on a private beach, on a yacht - it may depend on where you are, when the picture is taken, and whether the subjects can be seen freely by passers-by. If you have to go into the private space, or find an unusual viewpoint and use special equipment (long lenses) to secure the shot, they can take legal action for 'invasion of privacy' now in most countries. But if you can take the picture from a public area with a normal camera, you can use it. Example - a picture of a street with people sitting outside cafes eating. I sell these all the time, it is what tourist guides want to see. This month I have already sold:
The first one is on a KM D7D , nice colours - the second on a Nikon D80, really peculiar colours.
David