These SEZs have considerably less bureaucracy. They have power/water connections handled already and a single-window system for approvals.

China also has plenty of SEZs

They are not even remotely comparable to China's. There are some SEZ's that made up of just a couple of buildings. And they aren't limited to manufacturing, it's common for multinational companies to run their R&D out of them.

Source: Worked in a Bangalore SEZ for a large Chinese telecom company.