I suspect these units have a lot more robust build for an external install as well as all manner of bells and whistles not required for a home install. I bet it can be made a lot cheaper for interior residential type install. They will go through the cost reduction cycle that L2 chargers have/are going through.
Uhm... how much HAVE L2 chargers gone through? On an apples-to-apples basis, I mean. A Clipper Creek LCS-25P has gone from being a $1000 item to being a $500 item in five years, but almost all of that was basically "Oops, we have someone to compete with now" and they were less than $600 by 2013. It's not like 25 feet of flex-tolerant cable has gotten cheaper, and the cost of injection-molding a housing doesn't really change when you're only buying them a container load per year instead of per week. So thinking about how much power-handling materials for 25kw cost may be revealing for just how cheap DCFC actually can get. It might not be as flexible as one might like. Maybe it'll NEVER cost less than $5k just because you just need this much copper and this much steel tubing and you have to have a fireproof housing so it can never be injection-molded plastic and will always be a bent sheet-steel assembly, there always has to be a 100amp safety disconnect and those just cost $50 even when you buy a thousand of them, example etc.
Its not just a question of high use. Think about it. A 150kw battery for a heavy duty truck/SUV would take ~24 hours to full charge on present 7.2kw L2 chargers. Even a 25KW DCFC would take ~ 6 hours to full charge.
6 hours is plenty for "overnight". But most "heavy duty" trucks (in quotes because DOT says they're still light trucks) drive even few miles on average per year than cars do. And we know how little that is because that's what Volts are scoped to handle.