If you are asking why students choose Tamil Nadu for college, start here: for most engineering seats, Tamil Nadu uses TNEA, which is marks-based counselling, not a separate written exam. That means your Class 12 PCM marks matter more than coaching for one extra entrance test.
The state guide says the Main Entry Exam is TNEA (marks-based), and the academic route for most engineering seats is Class 12 with PCM for most engineering seats, admitted through TNEA primarily on marks rather than a separate written test. If you want the official route for engineering admission, read our full state guide for Tamil Nadu: Tamil Nadu college admissions guide.
This is a real advantage if you want less exam pressure. It does not mean admission is easy. It means the system is more straightforward for most engineering seats than states where you must clear a separate CET-style exam first.
There is one important exception: if you want IIT Madras or other centrally-funded institutes, you still need JEE Main / Advanced. For medical colleges in the state, the entrance exam is NEET UG.

