Many tech companies started in Beijing with obvious government boosts. There is also the major research universities (PKU and Qinghua at the top, many more at tiers just under). However, Beijing is also famous for government meddling and Black Audi-style privileged that is lacking in SZ and SH.

Take traffic for example, it is much saner in SH and SZ because the police can actually enforce the rules, whereas in BJ you get a asense they have given up because they feel like everyone is an official or is connected to one. It is a weird city even by Chinese standards.