The way I think about this is a typical up and to the right graph, of cost vs Speed. As you increase the speed, you increase the cost. So for real-time to be benefical to your business, you need to have be able to make more profit with data that is 1 second fresh vs 1 minute delayed. Looking at it like this, you can roughly group them: 50 milliseconds, 1 second, 1 minute, 1 hour, 1 day. In which area is your business for making profit? Uber showing a taxi location = 1 minute (perhaps fake it moving in between). Large electricity substation monitoring = 1 minute - assuming power down takes 5 minutes to commence. Trading with user interaction = 50ms. Then at each of those points are technology systems for deliverying that speed. I guess what some of these vendors are trying to do is change the shape of the graph. If they can bring the cost down massively, then more it may be worth Uber showing a 1 second update :) I know some users that watch the litle car obsessively.
