Compressed liquid systems don't explode so much, they tend to be way less catastrophic as they are a liquid. (The burst, or they spray out fluid)

Gas compressed things EXPLODE, or things that become gas on de-pressure. 10,000 psi is an insane pressure to have in a tank. Gas transmission pipelines operate at 1450 psi...

It's not an apples and oranges comparison. In the O&G industry we default to hydrotesting over pneumatic testing in basically all situations.