The Wikipedia article on them has a long list of countries using these in a variety of contexts [0], but that is not to say they are a good solution. NYPD is prevented from using them in alert mode due to the lawsuit that suggested physical harm was present in crowds where they were used. However, they can use them to make announcements, and they've been used in many crowd control scenarios in other parts of the World.

So, can someone explain why Thailand using them is explicitly of note?

[0] https://en.wikipedia.org/wiki/Long-range_acoustic_device

How about riot shield type gear for protection?

Edit. The countermeasure, according to an AI model is:

Avoid the direct beam of the LRAD by moving out of its narrow 15-degree coverage angle. Stepping off to the side drastically reduces exposure

Sound-dampening shields or barriers

Range style earmuffs and high-quality earplugs that attenuate sound significantly

What's notable is the level of propaganda and brainwashing of the populations, on both sides, and an 'if you're not echoing the propaganda maybe you're on their side', kind of atmosphere.

It's extraordinary to witness. I get a sense of how Germans must have got caught up in Nazi Germany, or at least, kept silent out of fear.