All first launch dates slip by quite a bit. This is just PR not keeping up with rocket reality1 :)
Rocketstar are building an aerospike engine, a concept that is decades behind conventional rocket motors in maturity & requires a lot of development work before it becomes reliable enough for paying customers. Blue Origin are going from a reusable technology demo (Shepard) to Falcon Heavy competitor (Glenn) which is a big step. Best of luck to them both
Space-X has taken the nearest thing to a risk free path, build a bog standard rocket2 for LEO insertions (Falcon-1), then make a bigger rocket capable of useful Geosynchronous insertions (Falcon-9), then make it reusable (the really hard bit!) to slash costs, then make it (much) bigger (Falcon-Heavy). What is astounding about Space-X is that it has managed all of these steps in only 18 years from start-up and is now fairly close to providing a bus timetable equivalent for launch dates.
1 Lookup Virgin Galactic for world leading slippage.
2 Not simple, a well known engineering model used since the 50's. (Atlas development is comparable)
Biting the hand that feeds IT
