Do you see expense changing with TL though? Surely independent robots that can seek out and extract materials using a variety of means, assuming their effective life enables a positive balance sheet, would mean that at the levels of Very High Tech, if not at High, resource extraction could be a pretty straightforward activity?
I just imagine the old days of the meteor miner going out with the industrial laser onto the rock surface are more primitive, while the higher-tech miner sits in his vessel monitoring the activities and status of a number of mining bots out there doing the grunt-work for him.
I'd think that at higher tech levels the operation is even more automated. A mining ship arrives, much like a fishing trawler, and releases automated mining modules that move to nearby asteroids, attach themselves, fill themselves with ore, and then return to the ship for pick up.
The modules take X days to fill up so the ship arrives with a fresh batch to release and picks up the now full ones. It then returns to a mother ship that collects a big number of the containers and takes them to the smelter or refining facility where they are unloaded and serviced. The mother ship is loaded with a fresh empty batch and returns to the asteroid field to distribute these to the mining ships.
The whole operation simply moves forward along the asteroid belt devouring it as they go. The refinery could be on a large asteroid turned into a mining ship that follows the operation.
I figured this out one time where you'd use the Type S scout converted to a seeker carrying 7 mining modules the size of standard shipping modules. The seeker in this case has no jump capacity. It doesn't need it.
The mother ships would be subsidized merchants with the passenger space converted to a sort of rest area for the seeker crews who would rotate work shifts. Empty modules go out the front of the cargo bay, full ones go in the back being pushed forward until the ship is full.
It then takes the off duty crews back along with full containers to the refinery, picks up new crews and empty containers and goes back out to repeat the process.
That means the mining is going 24/7 365 non-stop. I had the economics even figured out based on an article in Nat Geo on asteroids and the estimated value of their metals etc. where this all made pretty good credits.