Because no one has ever built one of those, and no one plans to build one of those, and none of those is currently funded. And it's not necessary for the job. On the other hand, fast turnaround suborbital vehicles have been demonstrated, of several designs, there are plans to build them, with high flight rates, the plans are funded, and the vehicles are under construction.
What more do you need to know?
Ok. I’ve stopped laughing now and I can type.
You state SOV have been demonstrated and they have fast turn around. Where is the information on the demonstration? I would like to read the specifics. What is fast turn around? What is the pay load? Who is funding them? Where are they being built?What is the altitude and how long is the flight (in time and distance for a round trip.
When you can post the article with all of this (or even most of this) information then I will post an apology for laughing at your unsubstantiated postings. Happy research.
Please don’t post fantasy. Need you to cite your facts. It sounds like a recurring theme, but in order to be considered seriously and not the Nutty professor, you need to back up your claims with verifiable references.