I think I've solved the mystery. You see, there is need for very specific sort of sand, which can only be found at a certain point on the seabed. They found the best way to extract it long term was an automated rail loop where driverless vehicles would reach the site, scoop up a full load and return to shore, where it would empty itself and the whole process would repeat. Unfortunately, being submersed in seawater all the time, maintaining and replacing these rails gets very expensive, and so the Prime Minister was lamenting the fact that a similar automated underwater digging set up that lacks rails does not exist.
What do they need this for in the first place, I hear you ask? Why, that's simple. A member of his very own cabinet (I assume) pledged to build the best sand castle in the galaxy, so naturally only the very best sand in the galaxy will suffice.