In the early days of stock exchanges the video displays were all driven using analogue video delivered over coax cable. However the video signal was merely there to deliver a blank screen, the actual data was done using TELETEXT decoder chipsets in the TV sets, with each page being assigned to different types of display. This gave a very robust data transfer, yet the actual hardware itself was simple enough and available off the shelf, and you could select any page at any time, and it would come up in sequence. The only change they did to the text standard was to use the entire frame of video to handle text, not just the top 3 lines of the screen normally blanked by the retrace circuit, so that they could transmit the entire 1000 page magazine very rapidly.
I had a job interview with the part of Logica that built those systems for the LSE around '85. The guy there told me that the reason they used teletext (apart from the good reasons you list) is that it's a broadcast standard : the same data goes to all the terminals at the same instant, not sent to one terminal after another by however fast a terminal i/o processor you might choose to use. Yes, the pages are sent serially one after another, but any given page is sent to all simultaneously.
As a result, there's no way the traders could complain that one person was getting data faster than any other. They all got it at the same time, down to the bit.