At my gym in Seattle, all of our fighters learn our short Wai Kru before their first fight. We have a longer Ram Muay as well, but rarely ever see/perform it. I asked to learn the full routine, and my kru smiled and said yes. There are not a lot of pure Muay Thai promotions out here in my part of the US (YET!), so a lot of the time you will fight on a kickboxing or mma promotion. In most cases, they don't let you perform anything pre-fight. You get in the ring/cage, touch gloves, bang it out, and leave. There isn't much more to it than that, sadly. Even for the bigger, televised Muay Thai events, they won't usually do a Wai Kru. We had a fighter on Lion Fight 21, and they didn't want to spend the television time on anything besides the walkout and fight.
There are some good Muay Thai promotions, and I love those shows. Wai Kru, mongkon, music...everything is on point. We just need more of them!