Counting large crowds is hard, but the tools continue to improve: we have increasingly advanced drone photography and access to better AI tools to generate more reliable estimates.

If crowd sizes become a significant point of contention it'll become increasingly commonplace for multiple parties to take lots of aerial video and photos that serve as independent verification. You could probably get a pretty accurate estimate of how many people show up to an event by sending drones to take photos every 15 minutes.

In any case, I think the problem you highlight is more focused towards the upper-end, while I was thinking about the lower end of the spectrum. Where some people might be very vocal online, but they're unable to gather more than a dozen or two people for any given protest. If a protest is gathering an unknown number of people that ranges between 100k and 1 million that sounds like a really good problem to have.

Your criticism of inconsistent people estimates are valid, I'm not sure if newspapers have published the set of tools and criteria that they use when generating these estimates, so that's an area where it would be great to see increased transparency.