Why are employers and recruiters so bad at communication?

So on Monday I drove down to a test centre for a role at a company. I had to do a series of assessments and at the end they said that they would let me know within the hour on whether or not I was successful. I heard nothing so I called them on Tuesday and they said that I had passed all the tests and would be letting me know in the next 24 hours the details of the next stage. Wednesday came and went with nothing so I called them on Thursday and she said that she was "waiting to hear back from the manager". This seems to have been the norm with all my applications - they never contact me when they say they will and their excuse is usually that 'they're waiting to hear from someone'. If that's the case then fine, but why can they not just tell me that? Honestly, it's so frustrating when I've made an effort to go out of my to get to an assessment or interview yet they can't even contact me on the day they said they would, even if not for a decision but just an update. It seems ironic that employers always say they're looking for good communication and organisational skills, yet they themselves seem to possess neither.