The question is not whether it is, it's whether it could be. Here's an example: the stock exchanges also need to handle huge amounts of concurrent and real-tim

The question is not whether it is, it's whether it could be. Here's an example: the stock exchanges also need to handle huge amounts of concurrent and real-time data (with much greater constraints on latency and correctness and linearizability than Uber's customers demand). They're not running on literally unchanged 50-year-old tech any more, but they're also not doing the sort of technology innovation that Uber's doing, and they're doing just fine.