Prevalent interview questions

I was reached out to after I applied for the role and we set up an interview. The interview went fairly well. The questions were not difficult. They said that they will send a case study to complete and will let me know if I am selected for the second interview. I sent them to case study back with my answer. I got the second interview which happened with the HR person again and someone in their UK office. This interview went well but a few points were interesting. The pay for the position is very low. It is lower by about $10k than the average in Canada. I asked them if that's up for negotiation or if there's a reason why that's the case. They responded with the fact that people stay in their company for only 1-2 years and move on. Which seems like a crazy thing to say to someone who is trying to work for you. They are basically saying that they don't care about retention and helping their employees grow with the company. They told me when I should receive a decision by. I did not hear back from them on the day I was supposed to. I waited until the end of the business day. I waited another day, still nothing. Next day, I sent them an email. They responded saying they would like to provide me with an update on the interview and that they will not be offering me the job. The fact that I've had 2 interviews with them and they didn't bother sending me an email, until after I followed up with them is very unprofessional. I think they didn't like that I asked about pay and that is probably why they didn't choose me.