Hello student this is because just like Jee main there's more entrance examination through which student get admission in engineering college and they are also recognized university so graduate from their also count while declaring the total graduate in B.tech every year.

Some of the top engineering entrance examination apart from jee main are as mentioned below -

1. VITEEE
2. SRMJEE
3. BITSAT
4. MET
5. COMEDK
6. AP EAMCET
7. KIITEE
8. MHTCET
9. WBJEE

For more details refer to the link mentioned below - https://www.google.com/amp/s/engineering.careers360.com/articles/top-engineering-entrance-exams-in-india/amp

Feel free to comment if you've any doubt

Good luck