Two phone screens then an onsite. The onsite was good at first, but then they started asking me questions that were way outside my professional experience (ie electrical engineering and mechanism design)

The recruiters gave me very specific instructions on a short 10 minute presentation. I prepared for this and had it down to the minute believing brevity and clarity were the skills being sought (for Elon world). The actual interview was over an hour long with highly confrontational questions that put me on the defensive. I had lots of backup data but they didn't want to see it. I left after the first round, not getting a chance to even start the other 1:1 stuff I had prepared. I had spent multiple meetings with two recruiters over the previous weeks. They told me exactly what to do and I deleted many extra details per their instructions. We even ran through practice scenarios about how it would go. It quickly became clear that the recruiters really do not coordinate with the interview team at all. As a manager and team lead I did the prescreening at my own company and had a >95% chance of bringing in a candidate who would be approved by the team - I never once ended the meeting early and sent them home. It is just a matter of putting in the time to ask the right questions and vet the candidate properly before the team meeting. If you are asked to go home after the first round then that is a total failing of the recruiting team; what are they even there for? Candidates may miss in the first round but I have seen most of them pull it out of the dumpster and give some very impressive presentations later in the day. Sending them home early is unprofessional and should never happen if they are screened properly and the team is in alignment. Cancelling the interview and sending qualified people home early is very unprofessional and shows you don't know what you are doing. It is a redflag and really doesn’t want to make people work for you. Also it is very easy to let the first 10 second impression make up your mind in an overtly subjective way. Is it their age or gender? Their ethnicity? Are they not neurotypical enough and bit too blunt for your fragile ego? The best hires I have had are the ones you are "difficult" in the interview and challenge me to be better; exactly what I want to hire them for. I don't hire obedience; I hire people who push the boundaries and make our company great. It's time to grow up and be professionals.