Deloitte Software Development Engineer In Test (SDET) interview questions

There was just a first telephone call with someone from the tech department, I believe he was the Tech Lead. The call lasted around 25-30 minutes and the questions were not so difficult based on the test automation approach, some competence questions and very few in depth technical ones. I received an email saying that they need to arrange another call, which I did. The call was just to inform me that I was not through to the second stage... I thought the first interview went well (apparently not) but why arrange just a simple call to tell me that I am rejected?! A simple email would be enough, since at the time being I was working on a different employer and had to go to a quiet place to speak, wasting a bit of time and effort. Not sure whether rejecting someone with a telephone call is better in general but for me an email would be enough...