LED Smart interview questions

First about personal work experiences and projects, then they asked two technical questions, one on C and one on circuits. Then they introduced what they do in the industry and asked me if I am interested.

I was called and asked for an interview the following day. I was interviewed by what seemed to be the owner and his wife, but it was hard to tell. They misunderstood some of my answers and I misunderstood some of their questions given which led to a few awkward pauses and disrupted the interview flow. They were friendly, but not overly and as much as I appreciated the interview and their time, I did not feel that it would be a culture fit for me personally. I was disappointed that they never contacted me after, even to let me know that they were going with another candidate. They said they would contact me, and it really bothers me when a company does not take the time to send a rejection letter at the very least. I find it unprofessional.