Why is Technical Recruiting so hard?

Why is Technical Recruiting so hard? I told them their salary was too low for someone with my experience. So, I referred a junior colleague for the position they were trying to get me to apply for. They wouldn't interview him. I asked and immediately received an interview the next day. I told them exactly why my colleague qualified for their position and gave direct examples of his skills/accomplishments. They asked what it would take to hire me. I said $40K more than the salary I knew he wanted/deserved. They said they would see what they could do. They hired him at the salary he wanted. See??? It's not really so hard, right?