Many countries did send experts...but only after the Thais panicked when they couldn’t solve it themselves.
UK, Americans, Chinese, Australians, etc.
It’s rainy season and the caves could be flooded for months...Water is murky/turgid and visibility near zero. You’ve got kids you have to train how to dive (some can’t even swim) in terrible conditions. That’s very dangerous for the kids if they freak out when diving out with two pros, it could also endanger the lives of the trained guys as well.
Complicated rescue situation with no easy answers if it continues to rain as expected.