Why are nurses making as much, if not more than some doctors (mainly post grad doctors)?

My job was looking for new RNs and I found out that one person that interviewed was offered $50/hr at another place he interviewed. Tf. They only have 4 years of education but are making almost as much as someone that has more education and responsibility

Why are nurses making as much, if not more than some doctors (mainly post grad doctors)?
Post Opinion