Don't have the technology? It's a block of salt. You just dig. I could understand if it had impurities like heavy metals maybe. Maybe something lost in translation. They could be talking more about having the technical training for it. Understanding cave-ins, potential for gas leaks, etc.
Also I think the translator is getting generations confused. The 2nd consort's father should be Mutsio's grandfather no?
ALOT of salt needs to be refined because of impurities.
But it is technically possible to just grab a hammer and bonk off the wall if you have a mine that is clean enough.
We only take like 1 % of salt mined for eating because we want to avoid impurities.
With no machines its going to be even less.
But the way it was translated could also be taken as lack of general knowledge of mining as a whole.
Translations are rarely perfect so its possible there was a mix up.