Lucky

There are a number of alloys that are used when working with desalinization plants, but the effective ones are cost prohibitive.

Even if they had a way of pumping it out cheaper, it still comes with issues that are costly. There are chemicals used during the process which pollute the brine and cost money to remove. It also comes out much warmer than surrounding water which disrupts the ecosystem. The brine eats up oxygen levels and suffocates animal life in the area.

They are trying to dilute the brine before releasing it back to the ocean but this is either not effective enough since you're using salt water from the same source you're pumping into, especially if the area doesn't have strong currents to carry it away. Or you're using water which doesn't have high salt levels and can dilute it to healthy levels, which you might as well just treat and use in the first place instead of using saltwater.

It's not an easy problem to solve at the moment

I'd be concerned about it leaching into the water table with that approach. Plus transport to those mines could be very expensive and complicated

Salt is highly corrosive, especially when concentrated into a slurry. If you dump it directly from shore you kill any local wildlife and destroy the local area before it dilutes. If you pipe it further out into the ocean the pipe will continually need maintenance due to corrosion and makes it more expensive

If you dump it on land you also need to ensure it isn't exposed to wind which will kick it up and cause health hazards to local populations. So you can bury it, but that doesn't scale and adds to the costs

All of that is fixable with the right policies

End zoning restrictions which requires all single family homes in a given area and allow mixed zoning. Minneapolis and the surrounding suburbs are doing this right now and there are apartments going up with the ground floor being shops, grocery stores, etc. Minneapolis is the first US city to rein in inflation below 2% because housing hasn't been as much of an issue. They started funding higher density housing back in 2018 and it is paying off tremendously right now.

One you build a few apartment buildings in the same area you can support bussing to the surrounding area, and most people can get around to where they need to for work.

Ideally you get light rail, but nimbyism is a huge pain that is hard to overcome. Still though, just getting to that point reduces the number of trips you need especially if you build bike trails to make short distance commuting even easier without a car.